tag:theconversation.com,2011:/global/topics/fast-radio-bursts-6352/articles
Fast radio bursts – The Conversation
2023-10-19T19:03:17Z
tag:theconversation.com,2011:article/214553
2023-10-19T19:03:17Z
2023-10-19T19:03:17Z
We traced a powerful radio signal to the most distant source yet – a galaxy billions of lightyears away
<p>Every day and night, hundreds of thousands of intense, brief flashes of radiation suddenly flicker on and then off all across the sky. These “fast radio bursts” are invisible to the naked eye, but to a radio telescope many almost outshine everything else in the sky for a few thousandths of a second. </p>
<p>Since the <a href="https://www.science.org/doi/10.1126/science.1147532">first such burst</a> was spotted in 2006, we have found that nearly all of them <a href="https://theconversation.com/how-we-closed-in-on-the-location-of-a-fast-radio-burst-in-a-galaxy-far-far-away-119177">come from distant galaxies</a>. Most bursts pass unnoticed, occurring outside the field of view of radio telescopes, and never occur again.</p>
<p>In new research published in <a href="https://science.org/doi/10.1126/science.adf2678">Science</a>, we have found the most distant fast radio burst ever detected: an 8-billion-year-old pulse that has been travelling for more than half the lifetime of the universe. </p>
<h2>Seizing the opportunity</h2>
<p>Astronomers are fascinated by fast radio bursts for two reasons. </p>
<p>The first is that <a href="https://theconversation.com/how-scientists-are-working-together-to-solve-one-of-the-universes-mysteries-106556">their cause is unknown</a>. The bursts are a trillion times more energetic than the things that look most like them: rotating neutron stars called pulsars, in our own galaxy.</p>
<p>The second reason is that the bursts provide a new tool to study <a href="https://theconversation.com/fast-radio-bursts-new-intergalactic-messengers-15700">other aspects of the cosmos</a>. </p>
<p>Fast radio bursts let us study the “cosmic web” of matter floating in the space between galaxies. This matter is very hot, diffuse gas and almost invisible, but it subtly slows down fast radio bursts as they pass through it. (This is ordinary matter, the same kind that makes up stars, planets and humans, not the invisible “dark matter” that also lurks throughout the universe.)</p>
<p>The degree to which bursts slow down correlates with the distance they have travelled.</p>
<p>In 2020, analysis of fast radio bursts revealed that the cosmic web actually contains <a href="https://theconversation.com/half-the-matter-in-the-universe-was-missing-we-found-it-hiding-in-the-cosmos-138569">more than half of the normal matter in the universe</a> – which astronomers had previously thought was “missing”.</p>
<h2>In search of the extreme</h2>
<p>More distant and extreme fast radio bursts promise to reveal further secrets about the universe, so astronomers are on the hunt. I lead a team <a href="https://theconversation.com/more-bright-fast-radio-bursts-revealed-but-where-do-they-all-come-from-104488">doing just that</a>, using the <a href="https://www.csiro.au/en/about/facilities-collections/atnf/askap-radio-telescope">Australian SKA Pathfinder (ASKAP)</a> radio telescope. </p>
<p>On June 6 2022, our team detected and pinpointed a very bright burst with a high degree of slowing (known officially as “FRB 20220610A”). Our initial calculations suggested it might be the most distant ever found. </p>
<p>However, there was a possibility that the burst was closer than we thought – or that it might come from a distant galaxy too faint to be seen with an optical telescope.</p>
<p>We turned to one of the world’s most powerful optical observatories to search for the host galaxy: the <a href="https://www.eso.org/public/teles-instr/paranal-observatory/vlt/">Very Large Telescope</a> (VLT) in Chile. The observatory’s four telescopes are equipped with cutting-edge cameras and spectrographs that can identify faint host galaxies and study their properties in detail. </p>
<p>At the position pinpointed by ASKAP as the source of the burst, initial images revealed faint smudges of light that looked like a distant galaxy. Analysing the spectrum of light from the galaxy showed it was strongly “redshifted”, meaning the emission from the burst has doubled in wavelength as it stretched out on its journey through the expanding universe.</p>
<p>The redshift had a value just over 1, which shows the burst was emitted more than 8 billion years ago, when the universe was less than half its present age. This confirmed that FRB 20220610A had broken the record for the most distant fast radio burst.</p>
<h2>Pushing the limits of the universe</h2>
<p>Like Olympic athletes, astronomers (including me) enjoy breaking records. Beyond personal satisfaction, however, this detection can also be used to explore the two fundamental questions about fast radio bursts. </p>
<p>First, the burst has the most energy of any that has been securely pinpointed to a location. It is more energy than our Sun puts out in 30 years, and approaches what we believe are fundamental physical limits.</p>
<p>The upper limit on the amount of energy any one fast radio burst can carry may be determined by quantum mechanical effects. At a certain point, the burst’s surge of radio photons may meet resistance from <a href="https://en.wikipedia.org/wiki/Dirac_sea">a sea of “virtual” electrons and positrons</a> which British physicist Paul Dirac predicted in 1930.</p>
<p>Our discovery also demonstrates the potential for fast radio bursts to study the composition of the distant universe. As we look back in time, we see the structure of galaxies changes a great deal. Bursts in distant galaxies may allow us to study the detailed structure of their hosts.</p>
<h2>Delving deeper in the cosmos</h2>
<p>We now know that energetic bursts exist in the distant universe. As new and upgraded telescopes join the hunt for fast radio bursts, we are likely to see many more tracked down to their host galaxies.</p>
<p>We are currently building a new fast radio burst search system for ASKAP which will make it five times more sensitive, enabling us to push the frontier of our research further out into the universe. </p>
<p>And in the future, ultra-sensitive radio telescopes such as the <a href="https://www.skao.int/en/science-users/science-working-groups-focus-groups/116/transients">Square Kilometre Array</a> (SKA) will be able to detect bursts at ever greater distances. These detections will be used to map the structure of the universe and resolve the tale of a modern astronomical mystery.</p><img src="https://counter.theconversation.com/content/214553/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Ryan Shannon receives funding from the Australian Research Council.</span></em></p>
A record-breaking discovery of an extreme ‘fast radio burst’ opens a window into the early universe.
Ryan Shannon, Associate Professor, Swinburne University of Technology, Swinburne University of Technology
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/180237
2023-09-28T19:58:35Z
2023-09-28T19:58:35Z
A search for links between two of the universe’s most spectacular phenomena has come up empty – for now
<figure><img src="https://images.theconversation.com/files/550815/original/file-20230928-28-yfqf00.jpg?ixlib=rb-1.1.0&rect=0%2C4%2C3000%2C1679&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.anu.edu.au/news/all-news/scientists-detect-a-black-hole-swallowing-a-neutron-star">Carl Knox / OzGrav</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span></figcaption></figure><p>Every so often, astronomers glimpse an intense flash of radio waves from space – a flash that lasts only instants but puts out as much energy in a millisecond as the Sun does in a few years. The origin of these “fast radio bursts” is <a href="https://theconversation.com/535-new-fast-radio-bursts-help-answer-deep-questions-about-the-universe-and-shed-light-on-these-mysterious-cosmic-events-161976">one of the greatest mysteries</a> in astronomy today. </p>
<p>There is no shortage of ideas to explain the cause of the bursts: a <a href="https://frbtheorycat.org/index.php/Main_Page">catalogue</a> of current theories shows more than 50 potential scenarios. You can take your pick from highly magnetised neutron stars, collisions of incredibly dense stars or many more extreme or exotic phenomena. </p>
<p>How can we figure out which theory is correct? One way is to look for more information about the bursts, using other channels: specifically, using ripples in the fabric of the universe called gravitational waves.</p>
<p>In <a href="https://iopscience.iop.org/article/10.3847/1538-4357/acd770">a new study</a> published in The Astrophysical Journal, we cross-referenced dozens of fast radio burst observations with data from gravitational wave telescopes to see if we could find any links.</p>
<h2>Gravitational wave astronomy</h2>
<p>If you think of telescopes, you probably think of ones that look for <a href="https://imagine.gsfc.nasa.gov/science/toolbox/multiwavelength1.html">electromagnetic signals</a> such as light, radio waves or x-rays. Lots of stars and other things in the cosmos produce these signals. But dust and gas abundant in the galaxies in which star systems reside can dim or block these signals.</p>
<p>Gravitational waves are different: they pass straight through matter, so nothing can really get in their way.</p>
<figure class="align-center ">
<img alt="An illustration showing a neutron star and a black hole about to collide, with light swirling around them." src="https://images.theconversation.com/files/550822/original/file-20230928-29-kzxcm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/550822/original/file-20230928-29-kzxcm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=424&fit=crop&dpr=1 600w, https://images.theconversation.com/files/550822/original/file-20230928-29-kzxcm.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=424&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/550822/original/file-20230928-29-kzxcm.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=424&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/550822/original/file-20230928-29-kzxcm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=533&fit=crop&dpr=1 754w, https://images.theconversation.com/files/550822/original/file-20230928-29-kzxcm.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=533&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/550822/original/file-20230928-29-kzxcm.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=533&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Researchers looked for gravitational waves from colliding pairs of neutron stars, as well as those from neutron stars and black holes, around the time and sky position of known fast radio bursts.</span>
<span class="attribution"><a class="source" href="https://outreach.ozgrav.org/portal2/gallery/#GmediaGallery_2-albums-25-153">Carl Knox / OzGrav</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>Astronomers have so far detected gravitational waves from colliding systems of compact stars such as <a href="https://theconversation.com/gravitational-waves-discovered-the-universe-has-spoken-54237">black holes</a> and <a href="https://theconversation.com/at-last-weve-found-gravitational-waves-from-a-collapsing-pair-of-neutron-stars-85528">neutron stars</a>, as well as discovering the engines behind <a href="https://theconversation.com/how-we-discovered-gravitational-waves-from-neutron-stars-and-why-its-such-a-huge-deal-85647">gamma-ray bursts</a>.</p>
<p>We also have reason to think fast radio bursts may produce gravitational wave signals.</p>
<h2>What produces fast radio bursts?</h2>
<p>Some fast radio bursts have been seen to repeat, but most are seen as single events. </p>
<p>For the repeating bursts, a recent <a href="https://theconversation.com/a-brief-history-what-we-know-so-far-about-fast-radio-bursts-across-the-universe-154381">simultaneous observation</a> of x-rays and a radio burst from a highly magnetised neutron star in our own Milky Way galaxy proves this type of star can produce fast radio bursts. No source has so far been identified for the non-repeaters.</p>
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Read more:
<a href="https://theconversation.com/a-brief-history-what-we-know-so-far-about-fast-radio-bursts-across-the-universe-154381">A brief history: what we know so far about fast radio bursts across the universe</a>
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<p>However, some theories involve astronomical objects and events we know produce strong gravitational waves. So if we have an idea of where in the sky a fast radio burst occurs, and when, we can do a targeted, sensitive search for gravitational waves over the same patch of sky. </p>
<h2>The CHIME radio telescope</h2>
<p>To look for new evidence on what causes fast radio bursts I co-led a targeted search using fast radio bursts detected by a radio telescope called <a href="https://theconversation.com/535-new-fast-radio-bursts-help-answer-deep-questions-about-the-universe-and-shed-light-on-these-mysterious-cosmic-events-161976">CHIME</a> in Canada.</p>
<p>As the <a href="https://www.chime-frb.ca/">CHIME/FRB</a> project has detected hundreds of fast radio bursts, there’s a good chance of catching one close enough to Earth to be observed by a gravitational wave telescope. This is important as fast radio bursts are so bright they can be seen from billions of light years away – much farther than present gravitational wave observatories can see.</p>
<p>So what did we do and how did we do it? The project team gave us the data for a few hundred fast radio bursts. As much of this data is still not publicly available, we signed a special agreement that we would not share the details outside the search teams. </p>
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Read more:
<a href="https://theconversation.com/535-new-fast-radio-bursts-help-answer-deep-questions-about-the-universe-and-shed-light-on-these-mysterious-cosmic-events-161976">535 new fast radio bursts help answer deep questions about the universe and shed light on these mysterious cosmic events</a>
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<p>We then estimated the distance to each fast radio burst, and searched for gravitational wave data around the 40 closest events (which had evidence of being within gravitational wave detector range).</p>
<p>Our search team was a small group of scientists from the LIGO gravitational wave observatory in the United States, the Virgo observatory in Italy, and collaborators from the fast radio burst team CHIME/FRB. </p>
<figure class="align-center ">
<img alt="A photo showing an array of radio antennas beneath a sunny sky." src="https://images.theconversation.com/files/550825/original/file-20230928-15-9i311a.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/550825/original/file-20230928-15-9i311a.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/550825/original/file-20230928-15-9i311a.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/550825/original/file-20230928-15-9i311a.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/550825/original/file-20230928-15-9i311a.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/550825/original/file-20230928-15-9i311a.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/550825/original/file-20230928-15-9i311a.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The CHIME radio telescope has detected hundreds of fast radio bursts.</span>
<span class="attribution"><span class="source">The CHIME Collaboration</span>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
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<p>We looked for gravitational wave signals around the sky position of each non-repeating fast radio burst around the time each occurred. For these non-repeaters, we did two kinds of search: one that looked for known gravitational wave signals, like those from colliding black holes or neutrons, and another that essentially looked for any burst of energy that was out of the ordinary.</p>
<p>For the repeating bursts, because we know that at least one such source is associated with a magnetised neutron star, we looked for the kind of gravitational wave signals we might expect from an isolated neutron star.</p>
<h2>What did we find out?</h2>
<p>Did we discover anything? Well, not this time. </p>
<p>It was not such a surprise, as we think fast radio bursts are much more common than detectable gravitational wave signals. In other words, gravitational wave sources would only account for a small fraction of fast radio bursts.</p>
<p>However, the closest fast radio burst in our sample was almost close enough for us to rule out the possibility it was caused by a collision between a neutron star and a black hole. Uncertainty in the distance to the burst means we can’t rule it out conclusively, but we are encourage by the fact the sensitive range of gravitational wave detectors is closing in on the distance to fast radio bursts.</p>
<h2>What next?</h2>
<p>Despite no definitive results this time, future searches could be a vital stepping stone to understanding fast radio bursts. </p>
<p>Gravitational wave detectors have become <a href="https://theconversation.com/gravitational-wave-detector-ligo-is-back-online-after-3-years-of-upgrades-how-the-worlds-most-sensitive-yardstick-reveals-secrets-of-the-universe-204339">more sensitive</a> than when we conducted this search, and will continue to improve in the coming years. This means they will allow a greater reach throughout the cosmos, so we can test a much larger sample of fast radio bursts. </p>
<p>We are also targeting future fast radio bursts from the known repeating source in our own galaxy mentioned above.</p>
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<p><em>Eric Howell would like to acknowledge the contribution towards this work by the other FRB-GW search co-chair Ryan Fisher; the other members of the paper writing team Kara Merfeld, Iara Tosta e Melo, Michael Patel; and the CHIME/FRB collaborators Shriharsh Tendulkar, Mohit Bhardwaj, Andrew Zwaniga, Adam Dong and Victoria Kaspi. The LIGO-Virgo GW analysts included Michael Patel, Patrick Sutton, Teresa Slaven-Blair, Amin Boumerdassi, Grace Johns, Nathan Ormsby, Max Elias Trevor, Adrian Helmling-Cornell, Hannah Griggs, Brandon Piotrzkowski, Benjamin Mannix, Kaemon Watada, Jacob Buchanan; the LIGO-Virgo review team were Tito Dal Canton, Marco Drag, Om Sharan Salafia, Ronaldas Macas and Michal Was.</em></p><img src="https://counter.theconversation.com/content/180237/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Eric Howell does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>
Massive flashes of energy known as ‘fast radio bursts’ have puzzled astronomers for years – and a new search for links to gravitational waves has so far found no connection.
Eric Howell, OzGrav Associate Investigator; Adjunct Research Fellow in Astrophysics, The University of Western Australia
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/203557
2023-05-24T21:06:10Z
2023-05-24T21:06:10Z
Astronomers detected two major targets with a single telescope – a mysterious signal and its source galaxy
<figure><img src="https://images.theconversation.com/files/521206/original/file-20230417-28-c0lcs2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">ASKAP multiple landscape backview.</span> <span class="attribution"><span class="source">CSIRO</span></span></figcaption></figure><p>Astronomers have been working to better understand the galactic environments of fast radio bursts (FRBs) – intense, momentary bursts of energy occurring in mere milliseconds and with unknown cosmic origins.</p>
<p>Now, a study of the slow-moving, star-forming gas in the same galaxy found to host an FRB <a href="https://doi.org/10.3847/1538-4357/acc1e3">has been published in The Astrophysical Journal</a>. This is only the fourth-ever publication on two completely different areas of astronomy describing the same galaxy. </p>
<p>Even more remarkable is the fact that a single telescope made the discovery possible – from the same observation. </p>
<h2>Fast radio mysteries</h2>
<p>FRBs, first detected in 2007, are incredibly powerful pulses of radio waves. They originate from distant galaxies, and the signal typically only lasts a few milliseconds.</p>
<p>FRBs are immensely useful for studying the cosmos, from investigating <a href="https://news.ucsc.edu/2020/05/missing-matter.html">the matter that makes up the universe</a>, to even using them <a href="https://academic.oup.com/mnras/article-abstract/516/4/4862/6694260">to constrain the Hubble constant</a> – the measure of how much the universe is expanding.</p>
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Read more:
<a href="https://theconversation.com/a-brief-history-what-we-know-so-far-about-fast-radio-bursts-across-the-universe-154381">A brief history: what we know so far about fast radio bursts across the universe</a>
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<p>However, the origin of FRBs is an ongoing puzzle for astronomers. Some FRBs are known to repeat, <a href="https://iopscience.iop.org/article/10.1088/1674-1056/aca7ed">sometimes over a thousand times</a>. Others have only been detected once.</p>
<p>Whether these repeating or non-repeating signals have formed differently <a href="https://academic.oup.com/mnras/article-abstract/500/3/3275/5944128">is currently being investigated by several research groups</a>. At one point, we had more theories on how fast radio bursts are made than detections of them.</p>
<p>It’s an exciting time to be studying FRBs, as showcased by the recent study <a href="https://theconversation.com/for-the-first-time-astronomers-have-linked-a-mysterious-fast-radio-burst-with-gravitational-waves-202341">associating an FRB with a gravitational wave</a>. If that finding holds true, it means at least some FRBs could be created by two neutron stars merging to form a black hole. </p>
<p>However, it is hard to pinpoint where exactly fast radio bursts come from. They are extremely bright yet so brief, getting an accurate position is hard for many radio telescopes. Without knowing where precisely these bursts originate, we cannot study the galaxies they are found in. And without knowing the environments FRBs are formed in, we cannot fully solve their mysteries. </p>
<p>One telescope in Australia is now helping us figure it out. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/521203/original/file-20230417-1956-ensh6k.jpg?ixlib=rb-1.1.0&rect=0%2C232%2C5725%2C3181&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/521203/original/file-20230417-1956-ensh6k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/521203/original/file-20230417-1956-ensh6k.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/521203/original/file-20230417-1956-ensh6k.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/521203/original/file-20230417-1956-ensh6k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/521203/original/file-20230417-1956-ensh6k.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/521203/original/file-20230417-1956-ensh6k.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">Some of the ASKAP dishes.</span>
<span class="attribution"><span class="source">CSIRO (Author provided)</span></span>
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<h2>The tool for the job</h2>
<p><a href="https://www.csiro.au/askap">CSIRO’s ASKAP radio telescope</a> (Australian Square Kilometre Array Pathfinder), located in the Western Australian desert, is a remarkable instrument. Made up of an array of 36 dishes separated by up to six kilometres, ASKAP can detect FRBs and <a href="https://astronomy.curtin.edu.au/research/craft/">pinpoint them to their host galaxies</a>. </p>
<p>ASKAP can in fact perform its FRB search at the same time as observations for other science surveys. <a href="https://wallaby-survey.org/">One such ASKAP survey</a> will map the star-forming gas in galaxies across the Southern sky, helping us understand how galaxies evolve. </p>
<p>During a recent observation for this survey, ASKAP also detected a new FRB, and we were able to identify the galaxy it comes from – a nearby <a href="https://astronomy.swin.edu.au/cosmos/S/spiral+galaxy">spiral galaxy</a> much like our own Milky Way. </p>
<h2>A gas-filled galaxy</h2>
<p>ASKAP was able to find the cold neutral hydrogen gas – the source of star formation – in this spiral galaxy. As far as FRB host galaxies go, this is already a rare detection of this gas; only three other cases have been published so far. These <a href="https://iopscience.iop.org/article/10.3847/2041-8213/ac4ca8">had required follow-up observations</a>, or <a href="https://iopscience.iop.org/article/10.3847/2041-8213/ac2b35">relied on other older observations</a>, made with different telescopes.</p>
<p>Here, ASKAP gave us both the FRB and the gas surrounding it. It is the first simultaneous detection of these rarely overlapping occurrences.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/521001/original/file-20230414-20-jqg7qh.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/521001/original/file-20230414-20-jqg7qh.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=495&fit=crop&dpr=1 600w, https://images.theconversation.com/files/521001/original/file-20230414-20-jqg7qh.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=495&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/521001/original/file-20230414-20-jqg7qh.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=495&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/521001/original/file-20230414-20-jqg7qh.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=622&fit=crop&dpr=1 754w, https://images.theconversation.com/files/521001/original/file-20230414-20-jqg7qh.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=622&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/521001/original/file-20230414-20-jqg7qh.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=622&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">ASKAP both found the cold hydrogen gas (white contours) in this spiral galaxy, and pinpointed an FRB near the centre (location given by the red ellipse). Glowacki et al. 2023; ESO and ASKAP.</span>
</figcaption>
</figure>
<p>Disturbed gas which ASKAP can detect can give us an indication that a galaxy merger recently happened, which tells us about the star forming history of the galaxy. In turn this gives us clues as to what may cause FRBs. </p>
<p>The previous studies of the gas surrounding FRBs found fast radio bursts reside in very dynamic systems, suggesting tumultuous galaxy mergers triggered the bursts.</p>
<p>For this particular FRB, however, the host galaxy environment is surprisingly calmer. Further studies will be needed to find out if overall we see disturbed gas environments for FRBs, or if there are distinct scenarios – and potentially multiple creation paths – for FRBs.</p>
<h2>More to come</h2>
<p>Given the uniqueness of such dual detections, this result showcases the strength and versatility of ASKAP. This is the first simultaneous detection of both an FRB and the gas in its host galaxy. </p>
<p>And this is just the start. ASKAP is set to detect and localise <a href="https://www.atnf.csiro.au/research/interferometry/public/How_CRACO_works.pdf">over a hundred FRBs a year</a>. By continuing to work collaboratively with each other, different survey groups will be able to untangle the mysteries behind FRBs, how they form, and their host galaxy environments. </p>
<hr>
<p><em>CSIRO acknowledges the Wajarri Yamaji as the Traditional Owners and native title holders of the Inyarrimanha Ilgari Bundara, our Murchison Radio-astronomy Observatory site, where ASKAP is located.</em></p><img src="https://counter.theconversation.com/content/203557/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Marcin Glowacki does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>
One of the few examples of a fast radio burst and the slow-moving, star forming gas in its origin galaxy has been linked together – thanks to observations from a CSIRO telescope.
Marcin Glowacki, Research Associate, Curtin University
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/204902
2023-05-11T20:08:05Z
2023-05-11T20:08:05Z
Flip-flopping magnetic fields hint at a solution for puzzling fast radio bursts from space
<figure><img src="https://images.theconversation.com/files/525288/original/file-20230510-23-sjc51m.jpg?ixlib=rb-1.1.0&rect=1040%2C1047%2C2185%2C1429&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Shutterstock</span></span></figcaption></figure><p>Fast radio bursts – intense, milliseconds-long flashes of radio energy from outer space – have <a href="https://www.pnas.org/doi/full/10.1073/pnas.1703512114">puzzled astronomers</a> since they were first spotted in 2007. A single burst can emit as much energy in its brief life as the Sun does in a few days.</p>
<p>The great majority of the short-lived pulses originate outside our Milky Way galaxy. We don’t know what produces most of them, or how. </p>
<p>In <a href="http://www.science.org/doi/10.1126/science.abo6526">new research published in Science</a>, we observed a repeating fast radio burst for more than a year and discovered signs it is surrounded by a strong but highly changeable magnetic field. </p>
<p>Our results suggest the source of this cosmic explosion may be a binary system made up of a neutron star whirling through winds of dense, magnetised plasma produced by a massive companion star or even a black hole.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/525534/original/file-20230511-21-ifg0v8.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="An infographic with heading 'Twisted Fields Around Mysterious Fast Radio Burst' shows an illustration of two radio telescopes, a bright object in the sky, and a chart." src="https://images.theconversation.com/files/525534/original/file-20230511-21-ifg0v8.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/525534/original/file-20230511-21-ifg0v8.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/525534/original/file-20230511-21-ifg0v8.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/525534/original/file-20230511-21-ifg0v8.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/525534/original/file-20230511-21-ifg0v8.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/525534/original/file-20230511-21-ifg0v8.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/525534/original/file-20230511-21-ifg0v8.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Changes in the magnetic field around a repeating fast radio burst hint at the nature of its origin.</span>
<span class="attribution"><span class="source">Di Li / ScienceApe / Chinese Academy of Science</span></span>
</figcaption>
</figure>
<h2>A fast radio burst that never stops repeating</h2>
<p>The repeating burst known as FRB 20190520B was <a href="https://www.nature.com/articles/s41586-022-04755-5">discovered in 2022</a> by astronomers at the Five-hundred-meter Aperture Spherical radio Telescope (FAST) in China. Repeating fast radio bursts are rare, but FRB 20190520B is the rarest of all: it is the only one that never rests, producing radio bursts a few times an hour, sometimes at multiple radio frequencies. </p>
<p>After this intriguing object was first found, astronomers rushed to follow up the initial observation using other radio wavelengths.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/more-bright-fast-radio-bursts-revealed-but-where-do-they-all-come-from-104488">More 'bright' fast radio bursts revealed, but where do they all come from?</a>
</strong>
</em>
</p>
<hr>
<p>Further investigation showed FRB 20190520B resides in an extremely dense environment in a dwarf galaxy 3.9 billion light years away. There are also materials surrounding the FRB source that produce strong, persistent radio emissions.</p>
<p>This led to suggestions that the bursting source is a young neutron star in a complex environment.</p>
<h2>Powerful magnetic fields</h2>
<p>What else can we learn about this intergalactic firecracker and its environment? We carried out observations of FRB 20190520B using CSIRO’s Parkes radio telescope, Murriyang, in New South Wales and the Green Bank Telescope in the United States. </p>
<p>To our surprise, FRB 20190520B turned out to produce strong signals at relatively high radio frequencies. These high-frequency signals turned out to be highly polarised - which means the electromagnetic waves are “waving” much more strongly in one direction than in others.</p>
<p>We found the direction of this polarisation changes at different frequencies. Measuring how much it changes tells us about the strength of the magnetic field the signal has travelled through. </p>
<p>As it turns out, this polarisation measure suggests the environment around FRB 20190520B is highly magnetised. And what’s more, the strength of the magnetic field appeared to vary over the 16 months we observed the source – and even flipped direction entirely twice. </p>
<p>This change in direction of the magnetic field around a fast radio burst has never been observed before.</p>
<h2>Filling in the picture</h2>
<p>What does this tell us about FRB 20190520B? Most popular theories to explain recent observations of repeating fast radio bursts involve binary systems made up of a neutron star and either another massive star or a black hole. </p>
<p>While we cannot rule out other hypotheses yet, our results favour the massive star scenario. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/a-brief-history-what-we-know-so-far-about-fast-radio-bursts-across-the-universe-154381">A brief history: what we know so far about fast radio bursts across the universe</a>
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</em>
</p>
<hr>
<p>Massive stars are known to have strong stellar winds with organised magnetic fields around them. If the source of the bursts were moving in and out of the stellar wind region as it travels through its orbit, we would expect the observed magnetic field direction to reverse. </p>
<p>The time scale of the magnetic field reversal, the measured variability in the apparent field strength, and the dense plasma surrounding the burst source all fit into this picture. </p>
<h2>What’s next?</h2>
<p>Our observations might provide crucial evidence to support the hypothesis that sources of repeating fast radio bursts have a massive companion capable of producing highly magnetised plasma. </p>
<p>More importantly, the binary hypothesis gives us a prediction for the future. If it is correct, the changes in polarisation of the radio signals from FRB 20190520B should rise and fall over longer periods of time. </p>
<p>So we will be watching. Future observations with Murriyang and the Green Bank Telescope will reveal whether FRB 20190520B is truly in a binary system – or whether the Universe will surprise us once again.</p><img src="https://counter.theconversation.com/content/204902/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Shi Dai receives funding from the Australian Research Council. He is affiliated with CSIRO Space and Astronomy and the National Astronomical Observatory of China. </span></em></p><p class="fine-print"><em><span>Reshma Anna-Thomas receives funding from NSF grant AAG-1714897. Reshma Anna-Thomas is affiliated with Department of Physics and Astronomy and Center for Gravitational Waves and Cosmology, West Virginia University, Morgantown, WV, USA. </span></em></p><p class="fine-print"><em><span>Di Li and Miroslav Filipovic do not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.</span></em></p>
Magnetic fields billions of light years away offer clues to the nature of intense flashes from the sky known as fast radio bursts.
Shi Dai, ARC DECRA Fellow, Western Sydney University
Di Li, Professor, National Astronomical Observatories, Chinese Academy of Sciences
Miroslav Filipovic, Professor, Western Sydney University
Reshma Anna-Thomas, PhD candidate Department of Physics and Astronomy, West Virginia University
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/202341
2023-03-27T19:00:47Z
2023-03-27T19:00:47Z
For the first time, astronomers have linked a mysterious fast radio burst with gravitational waves
<figure><img src="https://images.theconversation.com/files/517532/original/file-20230327-14-a7i9er.jpeg?ixlib=rb-1.1.0&rect=92%2C58%2C3138%2C1886&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">ASKAP.</span> <span class="attribution"><span class="source">CSIRO</span></span></figcaption></figure><p>We have <a href="https://www.nature.com/articles/s41550-023-01917-x">just published evidence</a> in Nature Astronomy for what might be producing mysterious bursts of radio waves coming from distant galaxies, known as <a href="https://theconversation.com/fast-radio-bursts-new-intergalactic-messengers-15700">fast radio bursts</a> or FRBs.</p>
<p>Two colliding <a href="https://theconversation.com/explainer-what-is-a-neutron-star-29341#:%7E:text=Origin%20of%20a%20neutron%20star&text=Once%20its%20nuclear%20fuel%20is,the%20mass%20of%20our%20sun.">neutron stars</a> – each the super-dense core of an exploded star – produced a burst of gravitational waves when they merged into a “<a href="https://www.ozgrav.org/news/research-highlight-the-aftermath-of-binary-neutron-star-mergers">supramassive” neutron star</a>. We found that two and a half hours later they produced an FRB when the neutron star collapsed into a black hole.</p>
<p>Or so we think. The key piece of evidence that would confirm or refute our theory – an optical or gamma-ray flash coming from the direction of the fast radio burst – vanished almost four years ago. In a few months, we might get another chance to find out if we are correct.</p>
<h2>Brief and powerful</h2>
<p>FRBs are incredibly powerful pulses of radio waves from space lasting about a thousandth of a second. Using data from a radio telescope in Australia, the Australian Square Kilometre Array Pathfinder (<a href="https://www.csiro.au/ASKAP">ASKAP</a>), <a href="https://www.science.org/doi/10.1126/science.aaw5903">astronomers have found</a> that most FRBs come from galaxies so distant, light takes <a href="https://theconversation.com/how-we-closed-in-on-the-location-of-a-fast-radio-burst-in-a-galaxy-far-far-away-119177">billions of years to reach us</a>. But what produces these radio wave bursts has been puzzling astronomers since <a href="https://www.science.org/doi/10.1126/science.1147532">an initial detection</a> in 2007.</p>
<p>The best clue comes from an object in our galaxy known as SGR 1935+2154. It’s a <a href="https://earthsky.org/space/what-is-a-magnetar/">magnetar</a>, which is a neutron star with magnetic fields about a trillion times stronger than a fridge magnet. On April 28 2020, it produced a <a href="https://www.nature.com/articles/s41586-020-2872-x">violent burst of radio waves</a> – similar to an FRB, although less powerful.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/a-brief-history-what-we-know-so-far-about-fast-radio-bursts-across-the-universe-154381">A brief history: what we know so far about fast radio bursts across the universe</a>
</strong>
</em>
</p>
<hr>
<p>Astronomers have long predicted that two neutron stars – a binary – merging to produce a <a href="https://theconversation.com/explainer-black-holes-7431">black hole</a> should also produce a burst of radio waves. The two neutron stars will be highly magnetic, and black holes cannot have magnetic fields. <a href="https://www.aanda.org/articles/aa/full_html/2014/02/aa21996-13/aa21996-13.html">The idea</a> is the sudden vanishing of magnetic fields when the neutron stars merge and collapse to a black hole produces a fast radio burst. Changing magnetic fields produce electric fields – it’s how most power stations produce electricity. And the huge change in magnetic fields at the time of collapse could produce the intense electromagnetic fields of an FRB.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/517530/original/file-20230327-14-ht1uqe.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A black field with two illustrations of galaxies in the foreground, and a yellow beam connecting them" src="https://images.theconversation.com/files/517530/original/file-20230327-14-ht1uqe.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/517530/original/file-20230327-14-ht1uqe.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=387&fit=crop&dpr=1 600w, https://images.theconversation.com/files/517530/original/file-20230327-14-ht1uqe.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=387&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/517530/original/file-20230327-14-ht1uqe.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=387&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/517530/original/file-20230327-14-ht1uqe.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=487&fit=crop&dpr=1 754w, https://images.theconversation.com/files/517530/original/file-20230327-14-ht1uqe.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=487&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/517530/original/file-20230327-14-ht1uqe.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=487&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Artist’s impression of a fast radio burst traveling through space and reaching Earth.</span>
<span class="attribution"><a class="source" href="https://www.eso.org/public/images/eso1915a/">ESO/M. Kornmesser</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<h2>The search for the smoking gun</h2>
<p>To test this idea, Alexandra Moroianu, a masters student at the University of Western Australia, looked for merging neutron stars detected by the Laser Interferometer Gravitational-Wave Observatory (<a href="https://www.ligo.org/index.php">LIGO</a>) in the US. The gravitational waves LIGO searches for are ripples in spacetime, produced by the collisions of two massive objects, such as neutron stars.</p>
<p>LIGO has found two binary neutron star mergers. Crucially, the second, known as <a href="https://www.ligo.org/detections/GW190425.php">GW190425</a>, occurred when a new FRB-hunting telescope called <a href="https://chime-experiment.ca/en">CHIME</a> was also operational. However, being new, it took CHIME two years <a href="https://theconversation.com/535-new-fast-radio-bursts-help-answer-deep-questions-about-the-universe-and-shed-light-on-these-mysterious-cosmic-events-161976">to release its first batch of data</a>. When it did so, Moroianu quickly identified a fast radio burst called <a href="https://www.chime-frb.ca/catalog/FRB20190425A">FRB 20190425A</a> which occurred only two and a half hours after GW190425.</p>
<p>Exciting as this was, there was a problem – only one of LIGO’s two detectors was working at the time, making it <a href="https://theconversation.com/weve-detected-new-gravitational-waves-we-just-dont-know-where-they-come-from-yet-116267">very uncertain</a> where exactly GW190425 had come from. In fact, there was a 5% chance this could just be a coincidence.</p>
<p>Worse, the <a href="https://fermi.gsfc.nasa.gov/">Fermi</a> satellite, which could have detected gamma rays from the merger – the “smoking gun” confirming the origin of GW190425 – was <a href="https://link.springer.com/article/10.1134/S1063773719110057">blocked by Earth</a> at the time.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/517525/original/file-20230326-14-fnkwc4.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A nighttime view of white curved pipes arranged in a grid pattern" src="https://images.theconversation.com/files/517525/original/file-20230326-14-fnkwc4.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/517525/original/file-20230326-14-fnkwc4.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/517525/original/file-20230326-14-fnkwc4.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/517525/original/file-20230326-14-fnkwc4.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/517525/original/file-20230326-14-fnkwc4.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/517525/original/file-20230326-14-fnkwc4.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/517525/original/file-20230326-14-fnkwc4.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">CHIME, the Canadian Hydrogen Intensity Mapping Experiment, has turned out to be uniquely suited to detecting FRBs.</span>
<span class="attribution"><span class="source">Andre Renard/Dunlap Institute/CHIME Collaboration</span></span>
</figcaption>
</figure>
<h2>Unlikely to be a coincidence</h2>
<p>However, the critical clue was that FRBs trace the total amount of gas they have passed through. We know this because high-frequency radio waves travel faster through the gas than low-frequency waves, so the time difference between them tells us the amount of gas.</p>
<p>Because we know the <a href="https://theconversation.com/half-the-matter-in-the-universe-was-missing-we-found-it-hiding-in-the-cosmos-138569">average gas density of the universe</a>, we can relate this gas content to distance, which is known as the <a href="https://www.nature.com/articles/s41586-020-2300-2">Macquart relation</a>. And the distance travelled by FRB 20190425A was a near-perfect match for the distance to GW190425. Bingo!</p>
<p>So have we discovered the source of all FRBs? No. There are not enough merging neutron stars in the Universe to explain the number of FRBs – some must still come from magnetars, like SGR 1935+2154 did.</p>
<p>And even with all the evidence, there’s still a one in 200 chance this could all be a giant coincidence. However, LIGO and two other gravitational wave detectors, <a href="https://www.virgo-gw.eu/">Virgo</a> and <a href="https://gwcenter.icrr.u-tokyo.ac.jp/en/">KAGRA</a>, will <a href="https://www.ligo.caltech.edu/page/observing-plans">turn back on</a> in May this year, and be more sensitive than ever, while CHIME and <a href="https://www.mwatelescope.org/">other radio telescopes</a> are ready to immediately detect any FRBs from neutron star mergers.</p>
<p>In a few months, we may find out if we’ve made a key breakthrough – or if it was just a flash in the pan.</p>
<hr>
<p><em>Clancy W. James would like to acknowledge Alexandra Moroianu, the lead author of the study; his co-authors, Linqing Wen, Fiona Panther, Manoj Kovalem (University of Western Australia), Bing Zhang and Shunke Ai (University of Nevada); and his late mentor, Jean-Pierre Macquart, who experimentally verified the gas-distance relation, which is now named after him.</em></p><img src="https://counter.theconversation.com/content/202341/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Clancy William James receives funding from the Australian Research Council. </span></em></p>
For years, astronomers have been detecting incredibly powerful pulses from the cosmos, without a confirmed source. Recent advances in astronomy are getting us closer to the solution.
Clancy William James, Senior Lecturer (astronomy and astroparticle physics), Curtin University
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/184634
2022-06-09T17:52:30Z
2022-06-09T17:52:30Z
Newly discovered fast radio burst challenges what astronomers know about these powerful astronomical phenomena
<figure><img src="https://images.theconversation.com/files/467838/original/file-20220608-26-hzbdb2.jpg?ixlib=rb-1.1.0&rect=8%2C866%2C4934%2C2834&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Researchers used a radio telescope in New Mexico to study a particularly interesting fast radio burst.</span> <span class="attribution"><a class="source" href="https://www.flickr.com/photos/dianasch/42831352202/in/photolist-28fRSMG-28eqRCT-2gij1gb-2mVkLCk-abPXeJ-mRBnWr-2nkk1HD-2mWEmz2-2meNv1Y-2mKaj3K-pC9Hhu-2mNuVQQ-56Jkta-2hu7JgN-2mZzZB8-BEVAUW-2mVoTaz-2mchThN-91rSYo-HHErwp-8eN6V4-abWktE-91oF7D-56JkqV-nZDA8K-DqoFyV-2jHHg2U-2juVMX6-of7i5L-2mtzGHF-2i9UMm7-T7hgaw-U7eWMd-2dNEVuC-2dugTrK-EEHmKy-2k5Jwdx-91rQbs-Ng5UdL-2kWVQh1-8snpug-UGDS2z-TBNsWE-6dRTJN-91rRzA-2aPaFTm-2kqAXBQ-TEHUBt-UDLB6b-2kNjNMS/">Diana Robinson/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span></figcaption></figure><p><em>The <a href="https://theconversation.com/us/topics/research-brief-83231">Research Brief</a> is a short take about interesting academic work.</em> </p>
<h2>The big idea</h2>
<p>A newly discovered fast radio burst has some unique properties that are simultaneously giving astronomers important clues into what may cause these mysterious astronomical phenomena while also calling into question one of the few things scientists thought they knew about these powerful flares, as my colleagues and I describe in a <a href="https://doi.org/10.1038/s41586-022-04755-5">new study</a> in Nature on June 8, 2022.</p>
<p>Fast radio bursts, or FRBs, are extremely bright pulses of radio waves that come from faraway galaxies. They release as much energy in a millisecond as <a href="https://theconversation.com/535-new-fast-radio-bursts-help-answer-deep-questions-about-the-universe-and-shed-light-on-these-mysterious-cosmic-events-161976">the Sun does over many days</a>. Researchers here at West Virginia University <a href="https://doi.org/10.1126/science.1147532">detected the first FRB back in 2007</a>. In the past 15 years, astronomers have detected around 800 FRBs, with <a href="https://doi.org/10.1007/s00159-019-0116-6">more being discovered every day</a>.</p>
<p>When a telescope captures an FRB, one of the most important features researchers look at is something called dispersion. Dispersion is basically a measure of how stretched out an FRB is when it reaches Earth. </p>
<p>The plasma that lies between stars and galaxies causes all light – including radio waves – to slow down, but lower frequencies feel this effect more strongly and slow down more than higher frequencies. FRBs contain a range of frequencies, so the higher frequency light in the burst hits Earth before the lower frequencies, causing the dispersion. This allows researchers to <a href="https://theconversation.com/535-new-fast-radio-bursts-help-answer-deep-questions-about-the-universe-and-shed-light-on-these-mysterious-cosmic-events-161976">use dispersion to estimate how far from Earth an FRB originated</a>. The more stretched out an FRB is, the more plasma the signal must have passed through, the farther away the source must be.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/467844/original/file-20220608-12-p4fex4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A diagram with six panels each showing a spike in a squiggly line and a shaded frequency diagram." src="https://images.theconversation.com/files/467844/original/file-20220608-12-p4fex4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/467844/original/file-20220608-12-p4fex4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=190&fit=crop&dpr=1 600w, https://images.theconversation.com/files/467844/original/file-20220608-12-p4fex4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=190&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/467844/original/file-20220608-12-p4fex4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=190&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/467844/original/file-20220608-12-p4fex4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=238&fit=crop&dpr=1 754w, https://images.theconversation.com/files/467844/original/file-20220608-12-p4fex4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=238&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/467844/original/file-20220608-12-p4fex4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=238&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The top of this diagram show six spikes in radio wave brightness that are six bursts from FRB190520. The bottom half shows the frequency range for each individual burst.</span>
<span class="attribution"><a class="source" href="https://doi.org/10.1038/s41586-022-04755-5">Niu, CH., Aggarwal, K., Li, D. et al.</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<h2>Why it matters</h2>
<p>The new FRB my colleagues and I discovered <a href="https://doi.org/10.1038/s41586-022-04755-5">is named FRB190520</a>. We found it using the <a href="https://doi.org/10.1007/s11433-006-0129-9">Five-hundred-meter Aperture Spherical Telescope</a> in China. An immediately apparent interesting thing about FRB190520 was that it is one of the only 24 repeating FRBs and repeats much more frequently than others – producing 75 bursts over a span of six months in 2020.</p>
<p>Our team then used the <a href="https://public.nrao.edu/telescopes/VLA/">Very Large Array</a>, a radio telescope in New Mexico, to further study this FRB and successfully pinpointed the location of its source – a dwarf galaxy roughly 3 billion light years from Earth. It was then that we started to realize how truly unique and important this FRB is. </p>
<p>First, we found that <a href="https://doi.org/10.1038/s41586-022-04755-5">there is a persistent, though much fainter, radio signal being emitted</a> by something from the same place that FRB190520 came from. Of the more than <a href="https://theconversation.com/535-new-fast-radio-bursts-help-answer-deep-questions-about-the-universe-and-shed-light-on-these-mysterious-cosmic-events-161976">800 FRBs discovered to date</a>, only one other has a similar persistent radio signal.</p>
<p>Second, since we were able to pinpoint that the FRB came from a dwarf galaxy, we were able to determine exactly how far away that galaxy is from Earth. But this result didn’t make sense. Much to our surprise, the distance estimate we made using the dispersion of the FRB was 30 billion light years from Earth, <a href="https://doi.org/10.1038/s41586-022-04755-5">a distance 10 times larger than the actual 3 billion light years to the galaxy</a>. </p>
<p>Astronomers have only been able to pinpoint the exact location – and therefore distance from Earth – <a href="http://frbhosts.org/#explore">of 19 other FRB sources</a>. For the rest of the roughly 800 known FRBs, astronomers have to rely on dispersion alone to estimate their distance from Earth. For the other 19 FRBs with known locations, the distances estimated from dispersion are very similar to the real distances to their source galaxies. But this new FRB shows that estimates using dispersion can sometimes be incorrect and throws many assumptions out the window.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/467843/original/file-20220608-12043-zp6ve6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="An image showing distant bright spots of stars and galaxies." src="https://images.theconversation.com/files/467843/original/file-20220608-12043-zp6ve6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/467843/original/file-20220608-12043-zp6ve6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=597&fit=crop&dpr=1 600w, https://images.theconversation.com/files/467843/original/file-20220608-12043-zp6ve6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=597&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/467843/original/file-20220608-12043-zp6ve6.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=597&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/467843/original/file-20220608-12043-zp6ve6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=750&fit=crop&dpr=1 754w, https://images.theconversation.com/files/467843/original/file-20220608-12043-zp6ve6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=750&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/467843/original/file-20220608-12043-zp6ve6.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=750&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">FRB190520 came from a small dwarf galaxy 3 billion light years away, marked by the cross hairs in the larger inset with the exact location of the FRB source in the circle in the smaller image.</span>
<span class="attribution"><a class="source" href="https://doi.org/10.1038/s41586-022-04755-5">Niu, CH., Aggarwal, K., Li, D. et al.</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<h2>What still isn’t known</h2>
<p>Astronomers in this <a href="https://doi.org/10.1007/s00159-019-0116-6">new field</a> still don’t know <a href="https://frbtheorycat.org/index.php/Main_Page">what exactly produces FRBs</a>, so every new discovery or piece of information is important.</p>
<p>Our new discovery raises specific questions, including whether persistent radio signals are common, what conditions produce them and whether the same phenomenon that produces FRBs is responsible for emitting the persistent radio signal. </p>
<p>And a huge mystery is why the dispersion of FRB190520 was so much greater than it should be. Was it due to something near the FRB? Was it related to the persistent radio source? Does it have to do with the matter in the galaxy where this FRB comes from? All of these questions are unanswered.</p>
<h2>What’s next</h2>
<p>My colleagues are going to focus in on studying FRB190520 using a host of different telescopes around the world. By studying the FRB, its galaxy and the space environment surrounding its source, we are hoping to find answers to many of the mysteries it revealed.</p>
<p>More answers will come from other FRB discoveries in the coming years, too. The more FRBs astronomers catalog, the greater the chances of discovering FRBs with interesting properties that can help complete the puzzle of these fascinating astronomical phenomena.</p><img src="https://counter.theconversation.com/content/184634/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Kshitij Aggarwal does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>
Astronomers studying fast radio bursts recently discovered one that repeats, has a persistent radio signal and originated in a galaxy much closer than it should have.
Kshitij Aggarwal, Affiliate Researcher in Astronomy and Astrophysics, West Virginia University
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/180595
2022-04-11T13:47:27Z
2022-04-11T13:47:27Z
Combined power of two telescopes is helping crack the mystery of eerie rings in the sky
<figure><img src="https://images.theconversation.com/files/457362/original/file-20220411-19-s6ezs4.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Some of the MeerKAT's 64 dishes, which astronomers use to collect huge amounts of data.</span> <span class="attribution"><span class="source">© South African Radio Astronomy Observatory (SARAO) </span></span></figcaption></figure><p>When astronomers dream of their ideal telescopes, it’s not that different to what people want from their TVs and computer monitors. Images they produce should be large and high definition, such as those from the Australian Square Kilometre Array Pathfinder (<a href="https://theconversation.com/the-australian-square-kilometre-array-pathfinder-finally-hits-the-big-data-highway-71217">ASKAP</a>), which have ~10k resolution (beyond the typical quality you get from digital TVs and digital cinematography). And they should have a high dynamic range, indicating high quality imaging with deep sensitivity to faint objects.</p>
<p>But not every telescope can do it all. That’s why complementary science – using some telescopes for some tasks, others for different but related tasks, and then combining the data – is so important in astronomy.</p>
<p>The value of complementary science is emphasised in <a href="https://arxiv.org/abs/2203.10669">our recent paper</a>. We worked with ASKAP and South Africa’s <a href="https://theconversation.com/africas-meerkat-first-light-images-have-blown-all-expectations-65246">MeerKAT telescope</a> to harness their different capabilities. In 2019, ASKAP discovered a rare and mysterious type of object, referred to as an “<a href="https://theconversation.com/wtf-newly-discovered-ghostly-circles-in-the-sky-cant-be-explained-by-current-theories-and-astronomers-are-excited-142812">odd radio circle</a>” (ORC). We didn’t know what these eerie glowing rings in the sky were. </p>
<p>It took data from MeerKAT to help us conclude that the circles are most likely enormous shells of gas, about a million light years across, emanating from the central galaxy.</p>
<figure class="align-center ">
<img alt="Graphic of the first odd radio circle discovered (ORC1) in a 2019 image from the Australian SKA Pathfinder (left), and the new detailed image from MeerKAT (right)." src="https://images.theconversation.com/files/456885/original/file-20220407-17-shyunu.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/456885/original/file-20220407-17-shyunu.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=248&fit=crop&dpr=1 600w, https://images.theconversation.com/files/456885/original/file-20220407-17-shyunu.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=248&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/456885/original/file-20220407-17-shyunu.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=248&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/456885/original/file-20220407-17-shyunu.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=312&fit=crop&dpr=1 754w, https://images.theconversation.com/files/456885/original/file-20220407-17-shyunu.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=312&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/456885/original/file-20220407-17-shyunu.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=312&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The first odd radio circle discovered (ORC1) in a 2019 image from the Australian SKA Pathfinder (left), and the new detailed image from MeerKAT (right).</span>
<span class="attribution"><span class="source">Author supplied</span></span>
</figcaption>
</figure>
<p>Neither the discovery nor the detail would have been possible without both telescopes. ASKAP’s uniquely large field of view enables the discovery of rare objects like ORCs. It also enabled the discovery of many new Fast Radio Bursts; <a href="https://theconversation.com/how-scientists-are-working-together-to-solve-one-of-the-universes-mysteries-106556">these are</a> seemingly rare, extremely bright and short-lived flashes of radio waves.</p>
<p>Meanwhile, MeerKAT’s unique sensitivity and sampling ability, achieved by its large number of dishes (64, located in a remote part of South Africa’s Northern Cape province), highly sensitive low noise amplifiers and large bandwidth, enables these objects to be studied in greater detail. MeerKAT is the best imaging radio telescope of its kind.</p>
<p>Both ASKAP and MeerKAT are precursors to the <a href="https://www.skatelescope.org/">Square Kilometre Array (SKA)</a>. This is a global project to build the world’s largest and most sensitive radio telescope within the coming decade, co-located in South Africa and Australia. As our new research makes clear, complementary science will be at the heart of the SKA. This is an exciting prospect for African science, with South Africans putting themselves forward as world leaders within radio astronomy. </p>
<h2>The nature of ORC1</h2>
<p>Our new paper focuses on the first ORC that ASKAP discovered in 2019. We call it ORC1. MeerKAT provided something critical to deepening our understanding of what it might be and how it formed: beautiful, detailed images.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/456060/original/file-20220404-13-vx4fdo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/456060/original/file-20220404-13-vx4fdo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=593&fit=crop&dpr=1 600w, https://images.theconversation.com/files/456060/original/file-20220404-13-vx4fdo.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=593&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/456060/original/file-20220404-13-vx4fdo.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=593&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/456060/original/file-20220404-13-vx4fdo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=746&fit=crop&dpr=1 754w, https://images.theconversation.com/files/456060/original/file-20220404-13-vx4fdo.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=746&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/456060/original/file-20220404-13-vx4fdo.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=746&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">ORC1 was rendered in more detail by the MeerKAT telescope.</span>
<span class="attribution"><span class="source">Jayanne English using data from MeerKAT and the Dark Energy Survey</span></span>
</figcaption>
</figure>
<hr>
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<em>
<strong>
Read more:
<a href="https://theconversation.com/odd-radio-circles-that-baffled-astronomers-are-likely-explosions-from-distant-galaxies-178290">'Odd radio circles' that baffled astronomers are likely explosions from distant galaxies</a>
</strong>
</em>
</p>
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<p>The data we collected from MeerKAT was run through a <a href="https://www.ursi.org/proceedings/procGA21/papers/URSIGASS2021-Mo-J11-AM2-3.pdf">complex workflow</a>. This was developed and provided by the <a href="https://www.idia.ac.za">Inter-University Institute for Data Intensive Astronomy (IDIA)</a>, a partnership of three South African universities. This specialised software enabled specific data products to be generated, such as images of ORC1’s polarisation and “radio colour”.</p>
<p>MeerKAT’s technology revealed three especially important and previously uncertain details about ORC1. First was the object’s internal structure, revealed for the first time due to MeerKAT’s deep sensitivity and high resolution. We can now see ORC1 contains multiple arcs, a radio source where the central galaxy is located, and knots of radio emission associated with other galaxies within the vicinity. </p>
<p>Our theory is that the central galaxy, a few billion light years away, caused the ORC during a particular event. This may have been the merging of supermassive black holes or a starburst event (the rapid forming of many stars within the galaxy) that occurred billions of years ago. It was during this event, we hypothesise, that the ORC expanded to its enormous size of about 1.6 million light years. </p>
<p>The second detail revealed by MeerKAT’s data relates to the ORC’s polarisation, made possible by its deep sensitivity.</p>
<p>All light from the electromagnetic spectrum is polarised: its magnetic and electric fields are oriented in a certain direction. However, <a href="https://www.britannica.com/science/wave-particle-duality">waves or photons</a> from an unpolarised source of light are randomly polarised – they do not tend toward any particular orientation. </p>
<p>Certain physical processes, such as the presence of magnetic fields, can polarise light. This causes some or all of the waves to be oriented in the same direction. We found that ORC1 is strongly polarised along its outer ring.</p>
<p>The third detail was the structure of ORC1’s spectral index or “radio colour”: how its brightness changes across frequency. </p>
<p>Typically, spectral index is measured with several radio telescopes combined, each observing at a different frequency that one can compare to see how the brightness changes. For large resolved sources like ORC1, there’s huge scope for uncertainty. MeerKAT’s large bandwidth enabled us to measure an “in-band” spectral index map across the entire source. Within this map, every pixel itself measures the spectral index across the many frequencies we’ve combined. Our resulting map showed a steep spectral index across both the ring and its internal structure, suggesting they may have been produced by the same mechanism.</p>
<p>These new details fit with an explanation where synchrotron radiation (electrons whizzing around magnetic fields) is causing the radio emission, from a shell of gas in the form of a spherical shock wave. However, the internal arcs and rings require further explanation. We hypothesised that these are caused by the nearby galaxies moving through the shell and leaving trails in their wake.</p>
<h2>New questions to pursue</h2>
<p>So, what does it all mean? As with so much radio astronomy, we’re not certain: more data and information added to the mystery, with some clues provided.</p>
<p>However, we have three hypotheses to explain the nature of ORCs. One: it’s a spherical shell from an expanding shock wave caused by a huge explosion, such as the coalescing of two supermassive black holes. Two: it’s a spherical shell from the “termination shock” of a previous “starburst” event – when many stars rapidly formed within the galaxy over a short period of time. Three: it may be a view from one end of powerful radio jets of highly energetic particles that spew out from near a central supermassive black hole.</p>
<p>Not having definite answers may strike some as frustrating. But this is the nature of some science. What’s exciting is that there’s more to come: the SKA, which is due to become operational within the coming decade, will probe even more deeply into faint, rare and mysterious objects. This almost guarantees the discovery of the unexpected, as we’ve seen throughout the history of science, and as we now see with ORCs. Future discoveries far above us may look faint – but the possibilities paint a bright future.</p><img src="https://counter.theconversation.com/content/180595/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jordan Collier works for the Inter-University Institute for Data-Intensive Astronomy. He is affiliated with Western Sydney University and CSIRO Astronomy and Space Science.</span></em></p>
Complementary science will be at the heart of the Square Kilometre Array.
Jordan Collier, ilifu Support Astronomer, Inter-University Institute for Data Intensive Astronomy
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/161976
2021-06-09T16:31:24Z
2021-06-09T16:31:24Z
535 new fast radio bursts help answer deep questions about the universe and shed light on these mysterious cosmic events
<figure><img src="https://images.theconversation.com/files/405212/original/file-20210608-10178-1xcfhaq.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C1007%2C600&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Mysterious blasts of radio waves from across the universe called fast radio bursts are getting more attention from astronomers.</span> <span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Artist%E2%80%99s_impression_of_a_fast_radio_burst_traveling_through_space_and_reaching_Earth.tif#/media/File:Artist%E2%80%99s_impression_of_a_fast_radio_burst_traveling_through_space_and_reaching_Earth.tif">ESO/M. Kornmesser</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p>On June 9, 2021, my colleagues and I announced the discovery of <a href="https://arxiv.org/abs/2106.04352">535 fast radio bursts</a> that we detected using the <a href="https://chime-experiment.ca/en">Canadian Hydrogen Intensity Mapping Experiment</a> telescope (CHIME). Detected in 2018 and 2019, these bursts of radio waves last only milliseconds, come from far across the universe, and are enormously powerful – a typical event releases as much energy in a millisecond as the Sun does over many days. </p>
<p>Fast radio bursts are the subject of <a href="https://doi.org/10.1007/s00159-019-0116-6">a young and emerging field in astrophysics</a>, with only around 150 having been found before the release of our new catalog. A lot of work has been done to understand these events, but these cosmic radio bursts remain as mysterious as when they were first <a href="https://doi.org/10.1126/science.1147532">discovered in 2007</a>. Simply put: <a href="https://frbtheorycat.org/index.php/Main_Page">No one knows what exactly produces them</a>. </p>
<p>Every newly captured event is allowing <a href="https://physics.wvu.edu/faculty-and-staff/faculty/emmanuel-fonseca">astrophysicists like me</a> to learn more about these weird cosmic phenomena. And, as this is happening, some astronomers have begun to use fast radio bursts as incredibly powerful tools to <a href="https://theconversation.com/half-the-matter-in-the-universe-was-missing-we-found-it-hiding-in-the-cosmos-138569">study the universe itself</a>. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/405215/original/file-20210608-10178-1plzhd7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A wave-shaped blue and yellow line." src="https://images.theconversation.com/files/405215/original/file-20210608-10178-1plzhd7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/405215/original/file-20210608-10178-1plzhd7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/405215/original/file-20210608-10178-1plzhd7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/405215/original/file-20210608-10178-1plzhd7.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/405215/original/file-20210608-10178-1plzhd7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/405215/original/file-20210608-10178-1plzhd7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/405215/original/file-20210608-10178-1plzhd7.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Fast radio bursts are enormously powerful blasts of energy from cosmological distances.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/sound-light-wave-royalty-free-image/155417795?adppopup=true">BlackJack3D/E+ via Getty Images</a></span>
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<h2>What is a fast radio burst?</h2>
<p>The name “fast radio burst” is pretty on the nose. These signals are bursts of radiation in radio frequencies that last for mere milliseconds. A defining property of these bursts is their dispersion: The bursts produce a spectrum of radio waves, and as the waves travel through matter, they spread out – or disperse – with bursts at higher radio frequencies arriving at telescopes earlier than those at lower frequencies. </p>
<p>This dispersion allows researchers to learn about two important things. First, telescopes like CHIME can measure this dispersion to learn about the stuff that radio bursts pass through as they travel toward Earth. For example, some of my colleagues were able to solve a long-standing <a href="https://theconversation.com/half-the-matter-in-the-universe-was-missing-we-found-it-hiding-in-the-cosmos-138569">mystery of missing matter</a> that was scattered across the universe. </p>
<p>Second, by measuring dispersion, astronomers can indirectly determine one of the most important pieces of information in all of astronomy: how far apart things are. The larger the dispersion measure, the more material the signal encountered. So, presumably, passing through more stuff means the burst traveled farther across the universe. </p>
<p>The dispersion measures for fast radio bursts are so large that astronomers know the signals must be coming from outside of the Milky Way galaxy, but these estimates can be inaccurate because of the uneven distribution of matter in the universe. We therefore needed another way of finding distances to the sources of fast radio bursts to avoid assumptions on how matter is distributed and thus unlock a large amount of information and opportunities. </p>
<p>A striking solution to this problem came in 2017, when colleagues of mine were able to pinpoint the <a href="https://doi.org/10.1038/nature20797">exact location of the source of a repeating fast radio burst</a> in the sky. By taking images of repeating bursts on the sky, they found <a href="https://doi.org/10.3847/2041-8213/834/2/L7">the specific galaxy</a> that the bursts were coming from. Then, using optical telescopes, they determined the distance to this galaxy – approximately 3 billion light-years away from Earth.</p>
<p>Repeating fast radio bursts make it much easier to pinpoint the host galaxies of their sources by giving researchers multiple chances to catch them. While astronomers work to answer important questions about fast radio bursts – What are they? Are repeating bursts different from single bursts? Are they all caused by the same things? – these lingering mysteries don’t stop us from putting them to good use in the meantime. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/405214/original/file-20210608-120786-xud8zv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A large white and black satellite dish shaped like a half-pipe." src="https://images.theconversation.com/files/405214/original/file-20210608-120786-xud8zv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/405214/original/file-20210608-120786-xud8zv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/405214/original/file-20210608-120786-xud8zv.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/405214/original/file-20210608-120786-xud8zv.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/405214/original/file-20210608-120786-xud8zv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/405214/original/file-20210608-120786-xud8zv.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/405214/original/file-20210608-120786-xud8zv.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The Canadian Hydrogen Intensity Mapping Experiment telescope has detected more fast radio bursts than any other telescope has.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Canadian_Hydrogen_Intensity_Mapping_Experiment_-_wire-mesh_half_pipe_reflector.jpg#/media/File:Canadian_Hydrogen_Intensity_Mapping_Experiment_-_wire-mesh_half_pipe_reflector.jpg">Z22/WikimediaCommons</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
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</figure>
<h2>Using fast radio bursts to study the cosmos</h2>
<p>The unique properties of fast radio bursts and their host galaxies – combined with recent technological advancements like the CHIME telescope – have given researchers hope that these phenomena can be used to answer some long-standing questions about the universe.</p>
<p>For example, some theorists have proposed that fast radio bursts can be used to study the <a href="https://doi.org/10.1103/PhysRevLett.115.121301">three–dimensional structure of matter</a> in the universe. Others have shown that the most distant bursts could be used to learn about <a href="https://doi.org/10.1093/mnras/stz571">poorly understood early moments</a> in the evolution of the universe. But to answer these and other questions, astronomers need a large number of fast radio bursts and their dispersion measures, strengths and locations in the sky. </p>
<p>And this is where our new catalog from CHIME comes in. By releasing information about 535 new fast radio bursts – including 61 bursts coming from 18 repeating sources – our team is more than quadrupling the total number of known events and pushing the field into an era of big data. With a large and growing number of measurements, all sorts of questions can finally start being addressed.</p>
<p>Recently, student members of the CHIME collaboration began releasing studies using this catalog. One study showed that the fast radio bursts detected by CHIME <a href="https://arxiv.org/abs/2106.04353">come equally from all directions</a> – a fact that had previously been <a href="https://doi.org/10.1088/2041-8205/789/2/L26">under</a> <a href="https://doi.org/10.1093/mnrasl/slw026">debate</a>. Another team studied the shapes and sizes of bursts in the catalog and confirmed that repeating events <a href="https://arxiv.org/abs/2106.04356">behave differently</a> from single bursts, pointing to multiple causes of fast radio bursts. And a third team for the first time confirmed that fast radio bursts are <a href="https://arxiv.org/abs/2106.04354">strongly associated with known galaxies</a>. This means astronomers can use events to map out the structure of the universe.</p>
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<a href="https://images.theconversation.com/files/405279/original/file-20210609-13-xui7yo.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A photo showing multiple galaxies and stars against the backdrop of space" src="https://images.theconversation.com/files/405279/original/file-20210609-13-xui7yo.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/405279/original/file-20210609-13-xui7yo.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=505&fit=crop&dpr=1 600w, https://images.theconversation.com/files/405279/original/file-20210609-13-xui7yo.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=505&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/405279/original/file-20210609-13-xui7yo.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=505&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/405279/original/file-20210609-13-xui7yo.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=634&fit=crop&dpr=1 754w, https://images.theconversation.com/files/405279/original/file-20210609-13-xui7yo.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=634&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/405279/original/file-20210609-13-xui7yo.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=634&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">One fast radio burst found by CHIME was determined to have come from the spiral arm of the red galaxy in the center of this photo, noted by the green circle.</span>
<span class="attribution"><a class="source" href="https://aasnova.org/2020/07/08/an-update-on-the-mysterious-flashes-of-frb-180916/">NSF’s Optical-Infrared Astronomy Research Laboratory/Gemini Observatory/AURA</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
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<h2>An adventurous future lies ahead</h2>
<p>CHIME and other telescopes are detecting more fast radio bursts every day, but researchers are just scratching the surface of what can be learned about – and done with – these mysterious and powerful cosmic events.</p>
<p>Colleagues of mine recently argued that attributing thousands of events to their individual host galaxies is “<a href="https://doi.org/10.1146/annurev-astro-091918-104501">the most urgent observational priority for [fast radio burst] science</a>.” Finding host galaxies is very challenging, though – only 14 galaxies that host fast radio bursts have been found so far. But other telescopes, like the <a href="https://www.atnf.csiro.au/projects/askap/index.html">Australian Square Kilometre Array Pathfinder</a>, have successfully detected and pinpointed a small number of nonrepeating bursts to their host galaxies. <a href="https://doi.org/10.5281/zenodo.3765414">Next-generation telescopes</a> are being designed to combine the high-detection capability of CHIME with the high-resolution imaging of the Australian telescope. </p>
<p>The field of fast radio burst astronomy is still in its infancy, and it is hard to predict what discoveries will be made next. But I expect the future of the field to be just like these profound cosmic events: bright and fast.</p>
<p>[<em>Understand new developments in science, health and technology, each week.</em> <a href="https://theconversation.com/us/newsletters/science-editors-picks-71/?utm_source=TCUS&utm_medium=inline-link&utm_campaign=newsletter-text&utm_content=science-understand">Subscribe to The Conversation’s science newsletter</a>.]</p><img src="https://counter.theconversation.com/content/161976/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Emmanuel Fonseca does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>
Fast radio bursts are the focus of a young and fascinating field of astronomy. Researchers just released data on more than 500 new bursts, quadrupling the total number of detected events.
Emmanuel Fonseca, Assistant Professor of Astronomy, West Virginia University
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/154381
2021-02-11T04:35:53Z
2021-02-11T04:35:53Z
A brief history: what we know so far about fast radio bursts across the universe
<figure><img src="https://images.theconversation.com/files/383653/original/file-20210211-14-1qn1hrd.jpg?ixlib=rb-1.1.0&rect=0%2C25%2C2480%2C1770&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.scienceimage.csiro.au/image/249/parkes-radio-telescope/">CSIRO/John Masterson</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span></figcaption></figure><p><a href="https://theconversation.com/au/topics/fast-radio-bursts-6352">Fast radio bursts</a> are one of the great mysteries of the universe. Since their discovery, we have learned a great deal about these intense millisecond-duration pulses.</p>
<p>But we still have much to learn, such as what causes them. </p>
<p>We know the intense bursts originate in galaxies billions of light years away. We have also used these bursts (called <a href="https://astronomy.swin.edu.au/cosmos/F/Fast+Radio+Bursts">FRB</a>s) to <a href="https://theconversation.com/half-the-matter-in-the-universe-was-missing-we-found-it-hiding-in-the-cosmos-138569">find missing matter</a> that couldn’t be found otherwise.</p>
<p>With teams of astronomers around the world racing to understand their enigma, how did we get to where we are now? </p>
<h2>The first burst</h2>
<p>The first FRB was discovered in 2007 by a team led by British-American astronomer <a href="https://physics.wvu.edu/faculty-and-staff/faculty/duncan-lorimer">Duncan Lorimer</a> using <a href="https://blog.csiro.au/parkes-telescope-indigenous-name/">Murriyang</a>, the traditional Indigenous name for the iconic Parkes radio telescope (image, top).</p>
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<a href="https://theconversation.com/silence-please-why-radio-astronomers-need-things-quiet-in-the-middle-of-a-wa-desert-118922">Silence please! Why radio astronomers need things quiet in the middle of a WA desert</a>
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<p>The team found an incredibly bright pulse — so bright that many astronomers did not believe it to be real. But there was yet more intrigue. </p>
<p>Radio pulses provide a tremendous gift to astronomers. By measuring when a burst arrives at the telescope at different frequencies, astronomers can tell the total amount of gas that it passed through on its journey to Earth.</p>
<figure class="align-center ">
<img alt="A curved graph, starting high top left and curving down low to bottom right." src="https://images.theconversation.com/files/381639/original/file-20210201-19-15wjt3o.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/381639/original/file-20210201-19-15wjt3o.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=366&fit=crop&dpr=1 600w, https://images.theconversation.com/files/381639/original/file-20210201-19-15wjt3o.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=366&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/381639/original/file-20210201-19-15wjt3o.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=366&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/381639/original/file-20210201-19-15wjt3o.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=459&fit=crop&dpr=1 754w, https://images.theconversation.com/files/381639/original/file-20210201-19-15wjt3o.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=459&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/381639/original/file-20210201-19-15wjt3o.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=459&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">A typical Fast Radio Burst. The burst arrives first at high frequencies and is delayed by as much as several seconds at the lower frequencies. This tell-tale curve is what astronomers are looking for.</span>
<span class="attribution"><span class="source">Ryan Shannon and Vikram Ravi</span></span>
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<p>The Lorimer burst had travelled through far too much gas to have originated in our galaxy, the Milky Way. The team concluded it came from a galaxy billions of light years away.</p>
<p>To be visible from so far away, whatever produced it must have released an enormous amount of energy. In just a millisecond it released as much energy as our Sun would in 80 years.</p>
<p>Lorimer’s team could only guess which galaxy their FRB had come from. Murriyang can’t pinpoint FRB locations very accurately. It would take several years for another team to make the breakthrough.</p>
<h2>Locating FRBs</h2>
<p>To pinpoint a burst location, we need to detect an FRB with a radio interferometer — an array of antennas spread out over at least a few kilometres.</p>
<p>When signals from the telescopes are combined, they produce an image of an FRB with enough detail not only to see in which galaxy the burst originated, but in some cases to tell where within the galaxy it was produced. </p>
<p>The first FRB localised was from a source that emitted many bursts. The first burst was discovered in 2012 with the giant <a href="http://www.naic.edu/">Arecibo telescope</a> in Puerto Rico.</p>
<p>Subsequent bursts were detected by the <a href="https://public.nrao.edu/telescopes/vla/">Very Large Array</a>, in New Mexico, and found to be coming from a tiny galaxy about 3 billion light years away.</p>
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<a href="https://images.theconversation.com/files/386907/original/file-20210301-23-1k5kkjz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Several dish-shipped antenna in the desert, all pointing up towards the sky in daylight." src="https://images.theconversation.com/files/386907/original/file-20210301-23-1k5kkjz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/386907/original/file-20210301-23-1k5kkjz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=401&fit=crop&dpr=1 600w, https://images.theconversation.com/files/386907/original/file-20210301-23-1k5kkjz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=401&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/386907/original/file-20210301-23-1k5kkjz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=401&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/386907/original/file-20210301-23-1k5kkjz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/386907/original/file-20210301-23-1k5kkjz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/386907/original/file-20210301-23-1k5kkjz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">Several of the ASKAP radio telescope antennas in WA.</span>
<span class="attribution"><span class="source">CSIRO</span>, <span class="license">Author provided</span></span>
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<p>In 2018, using the Australian Square Kilometre Array Pathfinder Telescope (<a href="https://www.csiro.au/en/Research/Facilities/ATNF/ASKAP">ASKAP</a>) in Western Australia, <a href="https://theconversation.com/how-we-closed-in-on-the-location-of-a-fast-radio-burst-in-a-galaxy-far-far-away-119177">our team identified the second FRB host galaxy</a>.</p>
<p>In stark contrast to the previous galaxy, this galaxy was very ordinary. But our <a href="https://science.sciencemag.org/content/365/6453/565" title="A single fast radio burst localized to a massive galaxy at cosmological distance">published discovery</a> was this month <a href="https://www.aaas.org/news/astronomical-discovery-earns-2020-aaas-newcomb-cleveland-prize">awarded a prize by the American Association for the Advancement of Science</a>. </p>
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<p>Teams including ours have now localised roughly a dozen more bursts from a wide range of galaxies, large and small, young and old. The fact FRBs can come from such a wide range of galaxies remains a puzzle. </p>
<h2>A burst from close to home</h2>
<p>On April 28, 2020, a flurry of X-rays suddenly bashed into the <a href="https://swift.gsfc.nasa.gov/">Swift</a> telescope orbiting Earth.</p>
<p>The satellite telescope dutifully noted the rays had come from a very magnetic and erratic neutron star in our own Milky Way. This star has form: it goes into fits every few years.</p>
<p>Two telescopes, <a href="https://chime-experiment.ca/en">CHIME</a> in Canada and the STARE2 array in the United States, detected a very bright radio burst within milliseconds of the X-rays and in the direction of that star. This demonstrated such neutron stars could be a source of the FRBs we see in galaxies far away.</p>
<p>The simultaneous release of X-rays and radio waves gave astrophysicists important clues to how nature can produce such bright bursts. But we still don’t know for certain if this is the cause of FRBs.</p>
<h2>So what’s next?</h2>
<p>While 2020 was the year of the local FRB, we expect 2021 will be the year of the the far-flung FRB, even further than already observed.</p>
<p>The CHIME telescope has collected by far the largest sample of bursts and is compiling a meticulous catalogue that should be available to other astronomers soon.</p>
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<strong>
Read more:
<a href="https://theconversation.com/how-we-closed-in-on-the-location-of-a-fast-radio-burst-in-a-galaxy-far-far-away-119177">How we closed in on the location of a fast radio burst in a galaxy far, far away</a>
</strong>
</em>
</p>
<hr>
<p>A team at Caltech is building an <a href="https://www.deepsynoptic.org/">array</a> specifically dedicated to finding FRBs.</p>
<p>There’s plenty of action in Australia too. We are developing a new burst-detection supercomputer for ASKAP that will find FRBs at a faster rate and find more distant sources.</p>
<p>It will effectively turn ASKAP into a high-speed, high-definition video camera, and make a movie of the universe at 40 trillion pixels per second.</p>
<p>By finding more bursts, and more distant bursts, we will be able to better study and understand what causes these mysteriously intense bursts of energy. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/0t0KoVhqz3Y?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">For the localisation of the first ‘one-off’ FRB, our team was awarded the 2020 Newcomb Cleveland Prize from the American Association for the Advancement of Science.</span></figcaption>
</figure><img src="https://counter.theconversation.com/content/154381/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Ryan Shannon receives funding from the Australian Research Council</span></em></p><p class="fine-print"><em><span>Keith Bannister receives funding from CSIRO and the Australian Research Council.</span></em></p>
Australian astronomers are part of a prize-winning team that was the first to pinpoint the location of a fast radio burst. But there is much we still don’t know about these mysterious bursts.
Ryan Shannon, Associate Professor, Swinburne University of Technology, Swinburne University of Technology
Keith Bannister, Astronomer, CSIRO
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/118922
2020-12-22T20:57:01Z
2020-12-22T20:57:01Z
Silence please! Why radio astronomers need things quiet in the middle of a WA desert
<figure><img src="https://images.theconversation.com/files/374698/original/file-20201214-15-1gentz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Panorama of the spectacular night sky over some of the ASKAP antennas at the MRO. </span> <span class="attribution"><span class="source">Credit: Alex Cherney/CSIRO</span>, <span class="license">Author provided</span></span></figcaption></figure><p>A remote outback station about 800km north of Perth in Western Australia is one of the best places in the world to operate telescopes that listen for radio signals from space.</p>
<p>It’s the site of CSIRO’s Murchison Radio-astronomy Observatory (<a href="https://www.csiro.au/en/Research/Astronomy/ASKAP-and-the-Square-Kilometre-Array/MRO">MRO</a>) and is home to three telescopes (and soon a fourth when half of the <a href="https://www.csiro.au/en/Research/Astronomy/ASKAP-and-the-Square-Kilometre-Array/SKA">Square Kilometre Array</a>, the world’s largest radio telescope, is built there). </p>
<p>But it’s important these telescopes don’t pick up any other radio signals generated here on Earth that could interfere with their observations.</p>
<p>That’s why the observatory was set up with strict rules on what can and can’t be used on site.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/282976/original/file-20190707-51273-o8b5yl.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Two people standing by a sign saying Radio Quiet Zone." src="https://images.theconversation.com/files/282976/original/file-20190707-51273-o8b5yl.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/282976/original/file-20190707-51273-o8b5yl.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/282976/original/file-20190707-51273-o8b5yl.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/282976/original/file-20190707-51273-o8b5yl.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/282976/original/file-20190707-51273-o8b5yl.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/282976/original/file-20190707-51273-o8b5yl.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/282976/original/file-20190707-51273-o8b5yl.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Me (left) and my colleague Carol Wilson at the signs marking the start of the Australian Radio Quiet Zone WA.</span>
<span class="attribution"><span class="source">CSIRO</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<h2>Listening to the sky</h2>
<p>One of the radio telescopes is the Australian Square Kilometre Array Pathfinder (<a href="https://www.csiro.au/en/Research/Facilities/ATNF/ASKAP?ref=/CSIRO/Website/Research/Astronomy/ASKAP-and-the-Square-Kilometre-Array/ASKAP">ASKAP</a>) operated by CSIRO. It’s actually an array of 36 individual antennas that work together as one large telescope.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/how-we-closed-in-on-the-location-of-a-fast-radio-burst-in-a-galaxy-far-far-away-119177">How we closed in on the location of a fast radio burst in a galaxy far, far away</a>
</strong>
</em>
</p>
<hr>
<p>ASKAP can capture high-quality images and <a href="https://theconversation.com/weve-mapped-a-million-previously-undiscovered-galaxies-beyond-the-milky-way-take-the-virtual-tour-here-148442">scan the whole sky</a>, a bit like a wide-angle lens allowing you to see more through a single viewpoint. It has already found a niche as a <a href="https://blog.csiro.au/explosions-in-the-sky-askap-detects-20-new-fast-radio-bursts/">finder</a> and <a href="https://blog.csiro.au/fast-radio-burst-traced-to-a-distant-galaxy/">localiser</a> of fast radio bursts. These are flashes of radio waves in space that last just milliseconds.</p>
<p>The MRO site also hosts the Curtin University-led Murchison Widefield Array (<a href="http://www.mwatelescope.org/">MWA</a>) telescope, which <a href="https://www.washington.edu/news/2020/06/11/epoch-reionization/">has been peering into the universe’s “dark ages”</a> and <a href="https://www.icrar.org/looking-for-ET/">finding no trace of aliens</a>.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/307853/original/file-20191219-11919-1qwlqmk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A series of antennas in the desert." src="https://images.theconversation.com/files/307853/original/file-20191219-11919-1qwlqmk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/307853/original/file-20191219-11919-1qwlqmk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/307853/original/file-20191219-11919-1qwlqmk.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/307853/original/file-20191219-11919-1qwlqmk.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/307853/original/file-20191219-11919-1qwlqmk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/307853/original/file-20191219-11919-1qwlqmk.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/307853/original/file-20191219-11919-1qwlqmk.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Antennas of the Murchison Widefield Array (MWA) low-frequency radio telescope.</span>
<span class="attribution"><span class="source">Dragonfly Media</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>The other radio telescope is Arizona State University’s <a href="https://loco.lab.asu.edu/edges/">EDGES</a>, which is looking for signals from the formation of stars and galaxies early in the universe.</p>
<p>These internationally recognised instruments detect mere whispers from space – radio waves that have travelled for billions of light-years before reaching Earth.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/307854/original/file-20191219-11951-1b77kxa.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A single piece of equipment in the desert location." src="https://images.theconversation.com/files/307854/original/file-20191219-11951-1b77kxa.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/307854/original/file-20191219-11951-1b77kxa.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/307854/original/file-20191219-11951-1b77kxa.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/307854/original/file-20191219-11951-1b77kxa.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/307854/original/file-20191219-11951-1b77kxa.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/307854/original/file-20191219-11951-1b77kxa.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/307854/original/file-20191219-11951-1b77kxa.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The Experiment to Detect the Global EoR Signature (EDGES) instrument.</span>
<span class="attribution"><span class="source">CSIRO</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>But their sensitivity exposes them to sources of unwanted radio frequency interference, known as RFI. </p>
<p>RFI can be caused by radio transmitters, such as mobile phones, CB radios or even wi-fi devices. Electrical equipment such as power tools can also be a problem. </p>
<h2>Way outback and beyond</h2>
<p>What makes the Murchison region an ideal operating environment for limiting RFI is the location has minimal human activity or occupancy. The <a href="https://www.murchison.wa.gov.au/">Murchison Shire</a> is the size of a small country but with a population of only 100 people. </p>
<p>The Shire covers an area of 49,500km² — roughly the size of the Netherlands in Europe. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/375288/original/file-20201216-17-uti6wb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A map showing the location of the observatory in Western Australia" src="https://images.theconversation.com/files/375288/original/file-20201216-17-uti6wb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/375288/original/file-20201216-17-uti6wb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=416&fit=crop&dpr=1 600w, https://images.theconversation.com/files/375288/original/file-20201216-17-uti6wb.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=416&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/375288/original/file-20201216-17-uti6wb.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=416&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/375288/original/file-20201216-17-uti6wb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=523&fit=crop&dpr=1 754w, https://images.theconversation.com/files/375288/original/file-20201216-17-uti6wb.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=523&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/375288/original/file-20201216-17-uti6wb.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=523&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The location of the MRO on Boolardy Station in WA.</span>
<span class="attribution"><span class="source">CSIRO</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>With the help of the Commonwealth and Western Australia governments, significant regulatory protection has been established to protect the site.</p>
<p>For example, the Australian Radio Quiet Zone Western Australia (<a href="https://www.atnf.csiro.au/projects/askap/ARQZWA.html">ARQZWA</a>), established by the Australian Communications and Media Authority, created a fixed zone around the MRO site to protect the telescopes from interference. Other groups intending to use transmitting equipment must seek permission first and follow any guidelines given.</p>
<h2>Switch off everything</h2>
<p>When staff go out to the site for the first time they get training about RFI, health and safety and indigenous culture.</p>
<p>Mobile phones need to be turned off at all times (which is fine, because it’s too far from any mobile towers to work anyway). </p>
<p>Bluetooth devices (wireless mice or fitness trackers) should be switched off or left behind, laptops should have Bluetooth and Wi-Fi switched off. The list goes on. </p>
<p>The MRO control building has a double RFI door to enter through – think airlock-style in any sci-fi movie.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/374636/original/file-20201213-23-y8qsun.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="One of the airlock style double doors." src="https://images.theconversation.com/files/374636/original/file-20201213-23-y8qsun.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/374636/original/file-20201213-23-y8qsun.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/374636/original/file-20201213-23-y8qsun.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/374636/original/file-20201213-23-y8qsun.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/374636/original/file-20201213-23-y8qsun.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/374636/original/file-20201213-23-y8qsun.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/374636/original/file-20201213-23-y8qsun.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The twin airlock-style RFI doors at the MRO control building.</span>
<span class="attribution"><span class="source">CSIRO</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>The site has a hybrid power station with solar panels that deliver up to 40% of the observatory’s power.</p>
<p>During the day, when the the clean energy system generates more power than the site requires, the excess energy is stored in a 2.5MWh lithium-ion battery, one of the largest in Australia. </p>
<p>The design specifications of the MRO power station ensure the facility contains the RFI generated by its own electronic systems.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/307858/original/file-20191219-11900-1g3u2z.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="The solar panel array in the middle of the desert." src="https://images.theconversation.com/files/307858/original/file-20191219-11900-1g3u2z.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/307858/original/file-20191219-11900-1g3u2z.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=337&fit=crop&dpr=1 600w, https://images.theconversation.com/files/307858/original/file-20191219-11900-1g3u2z.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=337&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/307858/original/file-20191219-11900-1g3u2z.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=337&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/307858/original/file-20191219-11900-1g3u2z.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=423&fit=crop&dpr=1 754w, https://images.theconversation.com/files/307858/original/file-20191219-11900-1g3u2z.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=423&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/307858/original/file-20191219-11900-1g3u2z.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=423&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Aerial view of the MRO power station, which has an array of 5,280 solar panels and battery with RFI shielding.</span>
<span class="attribution"><span class="source">CSIRO</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<h2>You can’t stop everything</h2>
<p>Unfortunately, as with all Earth-based locations, the telescopes receive RFI from orbiting satellites, which fall under international jurisdiction. The site also receives signals from aircraft safety beacons on commercial flights over the region. </p>
<p>Astronomers have developed software to remove this RFI from data as it usually overwhelms any astronomical signals. </p>
<p>We’ve also had several recorded occasions (usually during summer) when radio signals from as far away as Perth have been detected, due to atmospheric ducting. This is where the atmosphere effectively “guides” the radio waves much further than they would normally travel, due to changes in the atmospheric layers. Fortunately this is very rare. </p>
<p>The MRO has been in existence for about ten years, one of the newest such observatories in the world, but the 3,450km² Boolardy pastoral station on which it stands was established back in the 1850s.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/307859/original/file-20191219-11914-1c2vkzf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A lizard walking in front of the telescope equipment." src="https://images.theconversation.com/files/307859/original/file-20191219-11914-1c2vkzf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/307859/original/file-20191219-11914-1c2vkzf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/307859/original/file-20191219-11914-1c2vkzf.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/307859/original/file-20191219-11914-1c2vkzf.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/307859/original/file-20191219-11914-1c2vkzf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/307859/original/file-20191219-11914-1c2vkzf.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/307859/original/file-20191219-11914-1c2vkzf.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A goanna (or bangara in Wajarri Yamatji language) strolls past some of the antennas.</span>
<span class="attribution"><span class="source">ICRAR/Curtin</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>The traditional owners are the Wajarri Yamatji, who have lived in the region for tens of thousands of years. Together we negotiated an Indigenous Land Use Agreement (ILUA) in 2009 for the current telescopes, and we are negotiating a second one to allow the construction of the SKA.</p>
<p>Protection of the indigenous heritage is a significant component of this agreement and a major responsibility for the Australian government, CSIRO and the SKA organisation.</p>
<p>We also work collaboratively with neighbouring pastoralists to ensure they can carry on their daily work, including practices such as mustering, in a way that is compatible with radio astronomy. </p>
<h2>Visitors are not welcome</h2>
<p>Due to the remoteness of the MRO and the radio quiet rules and regulations, even those involved with the projects are discouraged from visiting (I’ve only been to the site once).</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/weve-mapped-a-million-previously-undiscovered-galaxies-beyond-the-milky-way-take-the-virtual-tour-here-148442">We've mapped a million previously undiscovered galaxies beyond the Milky Way. Take the virtual tour here.</a>
</strong>
</em>
</p>
<hr>
<p>Tourists are discouraged. We’ve distributed fact sheets to locals and visitor centres to explain this in more detail.</p>
<p>But you can visit the site remotely. We’ve created a cool techy replacement where you can take a <a href="https://virtualtours-external.csiro.au/MRO/">virtual tour of this unique and wondrous place</a>.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/301707/original/file-20191114-26207-m2978q.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A screengrab of the virtual tour of the site." src="https://images.theconversation.com/files/301707/original/file-20191114-26207-m2978q.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/301707/original/file-20191114-26207-m2978q.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/301707/original/file-20191114-26207-m2978q.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/301707/original/file-20191114-26207-m2978q.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/301707/original/file-20191114-26207-m2978q.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/301707/original/file-20191114-26207-m2978q.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/301707/original/file-20191114-26207-m2978q.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Take a virtual tour of the MRO site.</span>
<span class="attribution"><a class="source" href="https://virtualtours-external.csiro.au/MRO/">CSIRO</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure><img src="https://counter.theconversation.com/content/118922/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Kate Chow works for the Commonwealth Scientific and Industrial Research Organisation. </span></em></p>
Visitors are discouraged from the remote desert location where powerful telescopes are listening to the universe.
Kate Chow, Research Scientist, SKA Site & Infrastructure, CSIRO
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/138569
2020-05-27T15:16:24Z
2020-05-27T15:16:24Z
Half the matter in the universe was missing – we found it hiding in the cosmos
<figure><img src="https://images.theconversation.com/files/337121/original/file-20200522-124822-1fvly8h.jpeg?ixlib=rb-1.1.0&rect=0%2C77%2C3201%2C2075&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Diligence, technological progress and a little luck have together solved a 20 year mystery of the cosmos.</span> <span class="attribution"><span class="source">CSIRO/Alex Cherney</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span></figcaption></figure><p>In the late 1990s, cosmologists made a prediction about how much ordinary matter there should be in the universe. About 5%, they estimated, should be regular stuff with the rest a mixture of dark matter and dark energy. But when cosmologists counted up everything they could see or measure at the time, they came up short. By a lot. </p>
<p>The sum of all the ordinary matter that cosmologists measured only added up to about half of the 5% what was supposed to be in the universe.</p>
<p>This is known as the “missing baryon problem” and for over 20 years, <a href="https://scholar.google.com/citations?hl=en&user=04fD24sAAAAJ">cosmologists</a> <a href="https://scholar.google.com/citations?hl=en&user=uukAaXYAAAAJ">like us</a> looked hard for this matter without success.</p>
<p>It took the discovery of a new celestial phenomenon and entirely new telescope technology, but earlier this year, our team <a href="https://doi.org/10.1038/s41586-020-2300-2">finally found the missing matter</a>.</p>
<h2>Origin of the problem</h2>
<p>Baryon is a classification for types of particles – sort of an umbrella term – that encompasses protons and neutrons, the building blocks of all the ordinary matter in the universe. Everything on the periodic table and pretty much anything that you think of as “stuff” is made of baryons.</p>
<p>Since the late 1970s, cosmologists have suspected that dark matter – an as of yet unknown type of matter that must exist to explain the gravitational patterns in space – <a href="https://doi.org/10.1086%2F158003">makes up most of the matter of the universe</a> with the rest being baryonic matter, but they didn’t know the exact ratios. In 1997, three scientists from the University of California, San Diego, used the ratio of heavy hydrogen nuclei – hydrogen with an extra neutron – to normal hydrogen to estimate that <a href="https://doi.org/10.1038/381207a0">baryons should make up about 5% of the mass-energy budget of the universe</a>. </p>
<p>Yet while the ink was still drying on the publication, another trio of cosmologists raised a bright red flag. They reported that a direct measure of baryons in our present universe – determined through a census of stars, galaxies, and the gas within and around them – added up to only <a href="https://doi.org/10.1086/306025">half of the predicted 5%</a>. </p>
<p>This sparked the missing baryon problem. Provided the law of nature held that matter can be neither created nor destroyed, there were two possible explanations: Either the matter didn’t exist and the math was wrong, or, the matter was out there hiding somewhere.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/337124/original/file-20200522-124845-1jv4nre.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/337124/original/file-20200522-124845-1jv4nre.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/337124/original/file-20200522-124845-1jv4nre.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=300&fit=crop&dpr=1 600w, https://images.theconversation.com/files/337124/original/file-20200522-124845-1jv4nre.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=300&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/337124/original/file-20200522-124845-1jv4nre.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=300&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/337124/original/file-20200522-124845-1jv4nre.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=377&fit=crop&dpr=1 754w, https://images.theconversation.com/files/337124/original/file-20200522-124845-1jv4nre.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=377&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/337124/original/file-20200522-124845-1jv4nre.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=377&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Remnants of the conditions in the early universe, like cosmic microwave background radiation, gave scientists a precise measure of the unverse’s mass in baryons.</span>
<span class="attribution"><a class="source" href="https://en.wikipedia.org/wiki/File:WMAP_2010.png">NASA</a></span>
</figcaption>
</figure>
<h2>Unsuccessful search</h2>
<p>Astronomers across the globe took up the search and the first clue came a year later from theoretical cosmologists. Their computer simulations predicted that the majority of the missing matter was hiding in a <a href="https://doi.org/10.1086/306949">low-density, million-degree hot plasma that permeated the universe</a>. This was termed the “warm-hot intergalactic medium” and nicknamed “the WHIM.” The WHIM, if it existed, would solve the missing baryon problem but at the time there was no way to confirm its existence. </p>
<p>In 2001, another piece of evidence in favor of the WHIM emerged. A second team confirmed the initial prediction of baryons making up 5% of the universe by looking at tiny <a href="https://wmap.gsfc.nasa.gov/universe/bb_cosmo_fluct.html">temperature fluctuations</a> in the universe’s <a href="https://www.space.com/20330-cosmic-microwave-background-explained-infographic.html">cosmic microwave background</a> – essentially the leftover radiation from the Big Bang. With two separate confirmations of this number, the math had to be right and the WHIM seemed to be the answer. Now cosmologists just had to find this invisible plasma.</p>
<p>Over the past 20 years, we and many other teams of cosmologists and astronomers have brought nearly all of the Earth’s greatest observatories to the hunt. There were some false alarms and <a href="https://doi.org/10.1086/312644">tentative detections</a> of warm-hot gas, but one of our teams eventually linked those to <a href="https://doi.org/10.1088/0004-637X/740/2/91">gas around galaxies</a>. If the WHIM existed, it was too faint and diffuse to detect.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/337129/original/file-20200522-124822-10pb34e.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/337129/original/file-20200522-124822-10pb34e.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/337129/original/file-20200522-124822-10pb34e.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/337129/original/file-20200522-124822-10pb34e.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/337129/original/file-20200522-124822-10pb34e.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/337129/original/file-20200522-124822-10pb34e.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/337129/original/file-20200522-124822-10pb34e.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/337129/original/file-20200522-124822-10pb34e.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The red circle marks the exact spot that produced a fast radio burst in a galaxy billions of light-years away.</span>
<span class="attribution"><span class="source">J. Xavier Prochaska (UC Santa Cruz), Jay Chittidi (Maria Mitchell Observatory) and Alexandra Mannings (UC Santa Cruz)</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<h2>An unexpected solution in fast radio bursts</h2>
<p>In 2007, an entirely unanticipated opportunity appeared. <a href="https://scholar.google.com/citations?hl=en&user=MROPlzkAAAAJ">Duncan Lorimer</a>, an astronomer at the University of West Virginia, reported the serendipitous discovery of a cosmological phenomenon known as a <a href="https://doi.org/10.1126/science.1147532">fast radio burst (FRB)</a>. FRBs are extremely brief, highly energetic pulses of radio emissions. Cosmologists and astronomers still don’t know what creates them, but they seem to come from galaxies far, far away.</p>
<p>As these bursts of radiation traverse the universe and pass through gasses and the theorized WHIM, they undergo something called <a href="https://en.wikipedia.org/wiki/Dispersion_(optics)">dispersion</a>. </p>
<p>The initial mysterious cause of these FRBs lasts for less a thousandth of a second and all the wavelengths start out in a tight clump. If someone was lucky enough – or unlucky enough – to be near the spot where an FRB was produced, all the wavelengths would hit them simultaneously. </p>
<p>But when radio waves pass through matter, they are briefly slowed down. The longer the wavelength, the more a radio wave “feels” the matter. Think of it like wind resistance. A bigger car feels more wind resistance than a smaller car.</p>
<p>The “wind resistance” effect on radio waves is incredibly small, but space is big. By the time an FRB has traveled millions or billions of light-years to reach Earth, dispersion has slowed the longer wavelengths so much that they arrive nearly a second later than the shorter wavelengths.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/337131/original/file-20200522-124814-w4lwz7.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/337131/original/file-20200522-124814-w4lwz7.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/337131/original/file-20200522-124814-w4lwz7.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=337&fit=crop&dpr=1 600w, https://images.theconversation.com/files/337131/original/file-20200522-124814-w4lwz7.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=337&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/337131/original/file-20200522-124814-w4lwz7.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=337&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/337131/original/file-20200522-124814-w4lwz7.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/337131/original/file-20200522-124814-w4lwz7.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/337131/original/file-20200522-124814-w4lwz7.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Fast radio bursts originate from galaxies millions and billions of light-years away and that distance is one of the reasons we can use them to find the missing baryons.</span>
<span class="attribution"><a class="source" href="https://www.icrar.org/">ICRAR</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>Therein lay the potential of FRBs to weigh the universe’s baryons, an opportunity we recognized on the spot. By measuring the spread of different wavelengths within one FRB, we could calculate exactly how much matter – how many baryons – the radio waves passed through on their way to Earth.</p>
<p>At this point we were so close, but there was one final piece of information we needed. To precisely measure the baryon density, we needed to know where in the sky an FRB came from. If we knew the source galaxy, we would know how far the radio waves traveled. With that and the amount of dispersion they experienced, perhaps we could calculate how much matter they passed through on the way to Earth?</p>
<p>Unfortunately, the telescopes in <a href="https://doi.org/10.1126/science.1147532">2007 weren’t good enough</a> to pinpoint exactly which galaxy – and therefore how far away – an FRB came from.</p>
<p>We knew what information would allow us to solve the problem, now we just had to wait for technology to develop enough to give us that data.</p>
<h2>Technical innovation</h2>
<p>It was 11 years until we were able to place – or localize – our first FRB. In August 2018, our collaborative project called <a href="https://astronomy.curtin.edu.au/research/craft/">CRAFT</a> began using the <a href="https://www.atnf.csiro.au/projects/askap/index.html">Australian Square Kilometre Array Pathfinder (ASKAP)</a> radio telescope in the outback of Western Australia to look for FRBs. This new telescope – which is run by Australia’s national science agency, <a href="https://www.csiro.au/">CSIRO</a> – can watch huge portions of the sky, about 60 times the size of a full Moon, and it can simultaneously detect FRBs and pinpoint where in the sky they come from.</p>
<p>ASKAP captured its <a href="https://theconversation.com/how-we-closed-in-on-the-location-of-a-fast-radio-burst-in-a-galaxy-far-far-away-119177">first FRB</a> one month later. Once we knew the precise part of the sky the radio waves came from, we quickly used the <a href="http://www.keckobservatory.org/">Keck telescope</a> in Hawaii to identify which galaxy the FRB came from and how far away that galaxy was. The first FRB we detected came from a galaxy named <a href="https://doi.org/10.1126/science.aaw5903">DES J214425.25–405400.81 that is about 4 billion light-years away from Earth</a>, in case you were wondering.</p>
<p>The technology and technique worked. We had measured the dispersion from an FRB and knew where it came from. But we needed to catch a few more of them in order to attain a statistically significant count of the baryons. So we waited and hoped space would send us some more FRBs. </p>
<p>By mid-July 2019, we had detected five more events – enough to perform the first search for the missing matter. Using the dispersion measures of these six FRBs, we were able to make a rough calculation of how much matter the radio waves passed through before reaching earth.</p>
<p>We were overcome by both amazement and reassurance the moment we saw the <a href="https://doi.org/10.1038/s41586-020-2300-2">data fall right on the curve predicted by the 5% estimate</a>. We had detected the missing baryons in full, solving this cosmological riddle and putting to rest two decades of searching. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/337726/original/file-20200526-106832-1wn48l3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/337726/original/file-20200526-106832-1wn48l3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/337726/original/file-20200526-106832-1wn48l3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=584&fit=crop&dpr=1 600w, https://images.theconversation.com/files/337726/original/file-20200526-106832-1wn48l3.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=584&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/337726/original/file-20200526-106832-1wn48l3.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=584&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/337726/original/file-20200526-106832-1wn48l3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=734&fit=crop&dpr=1 754w, https://images.theconversation.com/files/337726/original/file-20200526-106832-1wn48l3.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=734&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/337726/original/file-20200526-106832-1wn48l3.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=734&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Sketch of the dispersion measure relation measured from FRBs (points) compared to the prediction from cosmology (black curve). The excellent correspondence confirms the detection of all the missing matter.</span>
<span class="attribution"><span class="source">Hannah Bish (University of Washington)</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>This result, however, is only the first step. We were able to estimate the amount of baryons, but with only six data points, we can’t yet build a comprehensive map of the missing baryons. We have proof the WHIM likely exists and have confirmed how much there is, but we don’t know exactly how it is distributed. It is believed to be part of a vast filamentary network of gas that connects galaxies termed “<a href="https://www.sciencenews.org/article/how-slime-mold-helped-scientists-map-cosmic-web-galaxies">the cosmic web</a>,” but with about 100 fast radio bursts cosmologists could start building an accurate map of this web. </p>
<p><em>This article was updated to indicate that Australia’s national science agency, CSIRO, operates the new telescope.</em></p>
<p>[<em>Insight, in your inbox each day.</em> <a href="https://theconversation.com/us/newsletters?utm_source=TCUS&utm_medium=inline-link&utm_campaign=newsletter-text&utm_content=insight">You can get it with The Conversation’s email newsletter</a>.]</p><img src="https://counter.theconversation.com/content/138569/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>J. Xavier Prochaska receives funding from the National Science Foundation.</span></em></p><p class="fine-print"><em><span>Jean-Pierre Macquart receives funding from the Australian Research Council. </span></em></p>
Cosmologists had only been able to find half the matter that should exist in the universe. With the discovery of a new astronomical phenomenon and new telescopes, researchers just found the rest.
J. Xavier Prochaska, Professor of Astronomy & Astrophysics, University of California, Santa Cruz
Jean-Pierre Macquart, Associate Professor of Astrophysics, Curtin University
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/119177
2019-06-27T20:44:14Z
2019-06-27T20:44:14Z
How we closed in on the location of a fast radio burst in a galaxy far, far away
<figure><img src="https://images.theconversation.com/files/281308/original/file-20190626-76717-1d2nqeo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A view from CSIRO’s Australian SKA Pathfinder (ASKAP) radio telescope antenna 29, with the phased array feed receiver in the centre, Southern Cross on the left and the Moon on the right. </span> <span class="attribution"><span class="source">CSIRO/Alex Cherney</span></span></figcaption></figure><p>Astronomers have spent the past dozen years hunting for fast radio bursts (FRBs) – flashes of radio waves that come from outer space and last just milliseconds. And after a dozen years of work we still don’t know exactly what causes them, only that it must be something very powerful, as they’ve clearly travelled a long way (billions of light-years).</p>
<p>FRBs are difficult to study because they’re unpredictable, hard to detect, and when you find one you need a special kind of telescope to get the right resolution to work out which galaxy it came from.</p>
<p>Most FRBs appear only once, although a couple of per cent of them are “repeaters” that reappear at the same spot in the sky (although not in any regular pattern).</p>
<p>In <a href="https://science.sciencemag.org/lookup/doi/10.1126/science.aaw5903">research published today</a> online in Science, we’ve managed to locate the home galaxy of a one-off FRB – the first time anyone has done this. In 2017, another team determined the home galaxy of a repeater, but that’s (relatively) easy job: it repeats, so you get a chance to point other telescopes at that spot on the sky. Our challenge was much harder.</p>
<p>Our FRB is called 180924. We determined it originated in a galaxy with the catchy name of DES J214425.25–405400.81, which is about 4 billion light years away in the constellation of Grus (the crane).</p>
<figure>
<iframe src="https://player.vimeo.com/video/344235808" width="500" height="281" frameborder="0" webkitallowfullscreen="" mozallowfullscreen="" allowfullscreen=""></iframe>
<figcaption><span class="caption">The discovery of the precise location of a powerful one-off burst of cosmic radio waves was made with CSIRO’s new Australian Square Kilometre Array Pathfinder (ASKAP) radio telescope in Western Australia. Credit: CSIRO/Sam Moorfield</span></figcaption>
</figure>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/fast-radio-bursts-new-intergalactic-messengers-15700">Fast Radio Bursts: new intergalactic messengers</a>
</strong>
</em>
</p>
<hr>
<h2>So how did we do it?</h2>
<p><a href="https://theconversation.com/askap-telescope-speeds-up-the-hunt-for-new-fast-radio-bursts-77481">For some years</a> we’ve been using CSIRO’s newest telescope, the Australian Square Kilometre Array Pathfinder (ASKAP), to <a href="https://www.nature.com/articles/s41586-018-0588-y/">find</a> quite a few <a href="https://theconversation.com/more-bright-fast-radio-bursts-revealed-but-where-do-they-all-come-from-104488">fast radio bursts</a>.</p>
<p>But in the past few months we’ve been setting up our new killer app, a “live action replay” that would let us localise an FRB for the first time.</p>
<p>One of us (Shivani) was working late one night, studying a previously discovered FRB and also monitoring the ongoing ASKAP observations. Around 1am she noticed that ASKAP’s software had stopped working, and ASKAP wasn’t recording any data. She restarted the software and headed to bed.</p>
<p>The next morning Shivani woke up, checked her inbox, and saw ASKAP had sent her a lovely message: it had found an FRB!</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/281293/original/file-20190626-81776-peqhxi.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/281293/original/file-20190626-81776-peqhxi.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/281293/original/file-20190626-81776-peqhxi.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=465&fit=crop&dpr=1 600w, https://images.theconversation.com/files/281293/original/file-20190626-81776-peqhxi.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=465&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/281293/original/file-20190626-81776-peqhxi.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=465&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/281293/original/file-20190626-81776-peqhxi.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=584&fit=crop&dpr=1 754w, https://images.theconversation.com/files/281293/original/file-20190626-81776-peqhxi.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=584&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/281293/original/file-20190626-81776-peqhxi.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=584&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Top panel: FRB180924 was only 1.3 milliseconds long. Bottom panel: This image shows the brightness of FRB180924 at different radio frequencies and times. The curved shape from top-left to bottom-right is due to an effect called dispersion. The gas the FRB travels through slows down the FRB at lower frequencies, causing it to arrive later. This effect allows astronomers to measure how much gas the FRB has gone through on its journey to the Earth.</span>
<span class="attribution"><span class="source">CSIRO/Shivani Bhandari</span></span>
</figcaption>
</figure>
<p>But it meant more than that: we knew that our new live action replay had worked, and we would finally be able to find out this FRB’s home.</p>
<p>Keith saw ASKAP’s message too, and ran cheering through his house, waking up his children (who were as pleased as he was, having lived through their dad’s quest for FRBs from day one).</p>
<p>Then followed a ten-day frenzy of data processing, coding, checking and double-checking. We would stop at nothing less than the name, address and phone number of this burst.</p>
<p>We split our team into two groups that worked independently. When it came time for the final check, we put two images on top of each other and they agreed. The two groups had localised this FRB to exactly the same part of the sky. We had determined its position to within the size of a galaxy. If there was a galaxy there, we would know the FRB’s home.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/more-bright-fast-radio-bursts-revealed-but-where-do-they-all-come-from-104488">More 'bright' fast radio bursts revealed, but where do they all come from?</a>
</strong>
</em>
</p>
<hr>
<h2>Home sweet home</h2>
<p>We searched an archive of optical images and quickly found a galaxy at the right spot. Then we notified our collaborators around the world, who had been waiting to trigger telescopes when we gave them a galaxy to look at.</p>
<p>They used three of the largest optical telescopes in the world – Keck, Gemini South, and the European Southern Observatory’s Very Large Telescope – to make a detailed image of the galaxy and take spectra (which give us its distance).</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/281309/original/file-20190626-76726-1l852tw.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/281309/original/file-20190626-76726-1l852tw.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/281309/original/file-20190626-76726-1l852tw.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=458&fit=crop&dpr=1 600w, https://images.theconversation.com/files/281309/original/file-20190626-76726-1l852tw.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=458&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/281309/original/file-20190626-76726-1l852tw.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=458&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/281309/original/file-20190626-76726-1l852tw.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=576&fit=crop&dpr=1 754w, https://images.theconversation.com/files/281309/original/file-20190626-76726-1l852tw.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=576&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/281309/original/file-20190626-76726-1l852tw.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=576&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">False color image of DES J514425.25-405400.81, the host galaxy of FRB 180924. This image was taken with the Very Large Telescope (VLT). FRB180924 came from somewhere inside the black circle, roughly 13,000 light years from the center of the galaxy.</span>
<span class="attribution"><span class="source">Curtin-ICRAR/Jean-Pierre Macquart</span></span>
</figcaption>
</figure>
<p>When the data came in, everything was a surprise. The only other “home” galaxy we had to compare it with was the repeater’s. Our FRB’s galaxy was 1,000 times bigger, and contained much older stars.</p>
<p>What’s more, our FRB came not from the centre of the galaxy, as some astronomers had expected, but from its outskirts (or at least its suburbs). At the very least, this means our FRB wasn’t produced by a gigantic black hole at the galaxy’s centre (one of the many ideas that’s been on offer).</p>
<p>Even with just a sample of two, we can say that FRBs have diverse home galaxies.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/the-search-for-the-source-of-a-mysterious-fast-radio-burst-comes-relatively-close-to-home-105735">The search for the source of a mysterious fast radio burst comes relatively close to home</a>
</strong>
</em>
</p>
<hr>
<h2>A cosmological goldmine</h2>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/281297/original/file-20190626-81780-1ls5xhv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/281297/original/file-20190626-81780-1ls5xhv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/281297/original/file-20190626-81780-1ls5xhv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=800&fit=crop&dpr=1 600w, https://images.theconversation.com/files/281297/original/file-20190626-81780-1ls5xhv.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=800&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/281297/original/file-20190626-81780-1ls5xhv.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=800&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/281297/original/file-20190626-81780-1ls5xhv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1005&fit=crop&dpr=1 754w, https://images.theconversation.com/files/281297/original/file-20190626-81780-1ls5xhv.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1005&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/281297/original/file-20190626-81780-1ls5xhv.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1005&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The Milky Way galaxy stretches above the core group of CSIRO’s Australian Square Kilometre Array Pathfinder (ASKAP) radio telescope.</span>
<span class="attribution"><span class="source">CSIRO/Alex Cherney</span></span>
</figcaption>
</figure>
<p>What’s more, now we can pinpoint where the bursts come from we can use them as tools.</p>
<p>FRBs interact with matter as they travel through space and are altered by all these encounters. We can “read” these alterations, combine them with how far the FRBs have come from, and work out how much matter they’ve met.</p>
<p>We hope that this will uncover the so-called “missing matter” that astronomers have been fretting over for years. This is not the notorious “dark matter” (whose nature we don’t know), but just run-of-the-mill baryonic matter that we think should be in space yet haven’t been able to detect very well. At long last we’ll be able to tidy up our cosmic accounting.</p>
<h2>What’s in store?</h2>
<p>The next task is to localise many FRBs so as to obtain enough to understand their cosmic evolution, the type of galaxies they come from and ultimately solve the mystery of their origins. The fun has just begun!</p><img src="https://counter.theconversation.com/content/119177/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Keith Bannister works for CSIRO. This project was supported by the Australian Research Council.
</span></em></p><p class="fine-print"><em><span>Shivani Bhandari works for CSIRO. </span></em></p>
For the first time scientists have located the home galaxy of a one-off fast radio burst. Here’s how they did it – and what they learned about the galaxy.
Keith Bannister, Astronomer, CSIRO
Shivani Bhandari, Research Postdoctoral fellow, CSIRO
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/106556
2018-11-27T13:17:44Z
2018-11-27T13:17:44Z
How scientists are working together to solve one of the universe’s mysteries
<figure><img src="https://images.theconversation.com/files/246628/original/file-20181121-161641-1rc00vw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">An artist’s impression of fast radio bursts in the sky above the Australian SKA precursor, ASKAP.</span> <span class="attribution"><span class="source">OzGrav, Swinburne University of Technology</span></span></figcaption></figure><p>One of the most baffling puzzles of modern astrophysics is the nature of Fast Radio Bursts, which were <a href="https://arxiv.org/pdf/0709.4301.pdf">discovered in 2007</a>. These are seemingly <a href="http://frbcat.org">rare</a>, extremely bright flashes of light with radio wavelengths. They last <a href="https://arxiv.org/pdf/0709.4301.pdf">only milliseconds</a>; <a href="https://arxiv.org/pdf/1504.00200.pdf">originate outside</a> our galaxy, the Milky Way; come from regions with <a href="https://arxiv.org/pdf/1801.03965.pdf">enormously strong magnetic fields</a>; and <a href="https://arxiv.org/pdf/1505.06220.pdf">pass through a significant amount of gas or dust</a> before reaching Earth. </p>
<p>All of these facts may make it sound as though scientists know a lot about Fast Radio Bursts. In reality, we don’t. For instance, though we know they’re not from our galaxy, we don’t know where exactly they come from. We don’t know what causes them. And we’re not sure whether they might be useful as <a href="https://arxiv.org/abs/1711.11277">cosmological</a> standards to measure the large scale properties of our universe.</p>
<p>Dozens of theories about Fast Radio Bursts have been proposed. Some conform to standard physics. Others are more exotic, including <a href="https://arxiv.org/abs/1807.01976">cosmic strings</a> – hypothetical, one-dimensional structures formed in the early universe – or even rather bizarre: one theory <a href="https://www.newscientist.com/article/2124209-could-fast-radio-bursts-really-be-powering-alien-space-ships">suggests</a> that aliens are responsible.</p>
<p>Now, in an attempt to discover the truth about Fast Radio Bursts, we have created <a href="https://frbtheorycat.org/index.php/Main_Page">a catalogue</a> that lists <a href="https://arxiv.org/abs/1810.05836">each theory</a>, along with its pros and cons. Scientists from around the world can weigh in, and new data and discoveries will be added throughout the process.</p>
<p>Some of this data will come from projects on the African continent, like the <a href="https://theconversation.com/new-telescope-chases-the-mysteries-of-radio-flashes-and-dark-energy-101607">Hydrogen Intensity and Real-time Analysis eXperient</a> (HIRAX), MeerKAT, and the Square Kilometre Array (SKA), which are expected to discover and localise thousands of Fast Radio Bursts.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/africas-meerkat-first-light-images-have-blown-all-expectations-65246">Africa's MeerKAT 'first light' images have blown all expectations</a>
</strong>
</em>
</p>
<hr>
<p>This platform will produce a great deal of knowledge. It will also provide valuable insight into scientific sociology as international researchers work together and ultimately, we hope, identify the most acceptable model. </p>
<h2>A range of theories</h2>
<p>Perhaps precisely because they are so elusive, Fast Radio Bursts have received a lot of attention from astronomers, astrophysicists, cosmologists, and physicists in the years since their discovery.</p>
<p>These are the main theories that have emerged so far. </p>
<ul>
<li><p>Fast Radio Bursts involve types of neutron stars, such as pulsars (which rotate rapidly) or magnetars (which are highly magnetised). These are probably the most plausible theories, since neutron stars’ intrinsic and extremely large magnetic fields can naturally fulfil the energy requirements for Fast Radio Bursts.</p></li>
<li><p>The merging of astronomical bodies (such as black holes, neutron stars and white dwarfs), and their collapse, has been proposed as a possible origin for Fast Radio Bursts.</p></li>
</ul>
<p>In such processes, enormous amounts of energy are released over short timescales. This could possibly create radiation akin to Fast Radio Bursts.</p>
<ul>
<li><p>some of the more exotic models have a more theoretical basis. They involve hypothetical objects such as quark stars (quarks are the subatomic particles that constitute neutrons and protons), axion stars (axions are extremely light, hypothetical subatomic particles), and <a href="https://science.nasa.gov/astrophysics/focus-areas/what-is-dark-energy">dark matter</a>: the hypothetical, unobserved matter that is believed to account for 27% of the total matter content of the universe. </p></li>
<li><p>Another fairly improbable theory is that Fast Radio Bursts are lightning striking on pulsars.</p></li>
</ul>
<p>And then there’s the suggestion that Fast Radio Bursts are evidence of aliens. It’s certainly the most unusual of the proposed theories, but it cannot be ruled out as a possibility yet.</p>
<p>Although it’s unlikely, Fast Radio Bursts may be signals from a beacon set up by an extraterrestrial civilisation, or perhaps from light sails that harness photons to travel across the galaxy. </p>
<p>There’s a remarkable variation in these models, and it’s hard work to narrow down the options and reach consensus. Of the 50 theories or models proposed to date, only three have been eliminated. This is what prompted us to set up the catalogue and to invite engagement from the broader scientific community.</p>
<h2>Platform for debate</h2>
<p>It’s no easy task to get scientists talking to each other about Fast Radio Bursts. That’s because the scientists in question have different specialisations and are from all over the world. </p>
<p>The online catalogue provides a suitable and accessible platform for discussion, debate, and the sharing of knowledge. There is also a traceable history, which creates an opportunity for us to study how as humans we work together to solve scientific problems – and perhaps how this process can be optimised in the future. </p>
<p>Part of our motivation, as theoretical physicists, was to develop this engagement and to dive in ourselves. The problems are rich and the waters are deep. </p>
<p>Data about Fast Radio Bursts is starting to pour in now, thanks to such game-changers as MeerKAT and HIRAX. As it arrives, is examined and papers are published, we’ll be able to start ruling out theories and digging deeper into viable theories. Within five years, this mystery could be solved.</p><img src="https://counter.theconversation.com/content/106556/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Emma Platts is supported by a PhD fellowship from the South African National Institute for Theoretical Physics (NITheP).</span></em></p><p class="fine-print"><em><span>Amanda Weltman receives funding from The Department of Science and Technology and the National Research Foundation of South Africa. She is a member of the Global Young Academy and a Next Einstein Forum Laureate. </span></em></p>
Perhaps precisely because they are so elusive, Fast Radio Bursts have received a lot of attention in the years since their discovery.
Emma Platts, PhD Student, University of Cape Town
Amanda Weltman, South African Research Chair in Physical Cosmology, Department of Mathematics and Applied Mathematics, University of Cape Town
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/105735
2018-10-30T02:43:08Z
2018-10-30T02:43:08Z
The search for the source of a mysterious fast radio burst comes relatively close to home
<figure><img src="https://images.theconversation.com/files/242676/original/file-20181029-76408-1p0d3f5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Antennas of CSIRO’s Australian SKA Pathfinder (ASKAP) radio telescope first picked up the Fast Radio Burst.</span> <span class="attribution"><span class="source">CSIRO/Alex Cherney</span>, <span class="license">Author provided</span></span></figcaption></figure><p>Fast radio bursts (FRBs) are just that – enormous blasts of radio waves from space that only last for a fraction of a second. This makes pinpointing their source a huge challenge. </p>
<p>Our team recently <a href="https://theconversation.com/more-bright-fast-radio-bursts-revealed-but-where-do-they-all-come-from-104488">discovered 20 new FRBs</a> using CSIRO’s <a href="https://www.csiro.au/en/Research/Facilities/ATNF/ASKAP">Australian Square Kilometre Array Pathfinder</a> in the Western Australian outback, almost doubling the known number of FRBs.</p>
<p>In follow-up research, published <a href="http://iopscience.iop.org/article/10.3847/2041-8213/aae7cb/meta">today</a> in The Astrophysical Journal Letters, we have taken one of these new detections – known as FRB 171020 (the day the radio waves arrived at Earth: October 20, 2017) – and narrowed down the location to a galaxy close to our own.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/more-bright-fast-radio-bursts-revealed-but-where-do-they-all-come-from-104488">More 'bright' fast radio bursts revealed, but where do they all come from?</a>
</strong>
</em>
</p>
<hr>
<p>This is the closest FRB detected (so far) but we still don’t know what causes these mysterious radio bursts that can contain more energy than our Sun produces in decades.</p>
<h2>Waves in space</h2>
<p>As radio waves travel through the universe they pass through other galaxies and our own Milky Way before arriving at our telescopes.</p>
<p>The longer radio wavelengths are slowed down more than the shorter wavelengths, meaning that there is a slight delay in the arrival time of longer wavelengths.</p>
<p>This difference in arrival times is called the dispersion measure and indicates the amount of matter the radio emission has travelled through.</p>
<figure>
<iframe src="https://player.vimeo.com/video/293891308" width="500" height="281" frameborder="0" webkitallowfullscreen="" mozallowfullscreen="" allowfullscreen=""></iframe>
<figcaption><span class="caption">An FRB’s journey to Earth.</span></figcaption>
</figure>
<p>FRB 171020 has the lowest dispersion measure of any FRB detected to date, meaning that it hasn’t travelled from half way across the universe like most of the other FRBs detected so far. That means it originated from relatively nearby (by astronomical standards).</p>
<p>By using models of the distribution of matter in the universe we can put a hard limit on how far the radio signal has travelled. For this particular FRB, we estimate that it could not have originated from further than a billion light years away, and likely occurred much closer. (Our <a href="https://imagine.gsfc.nasa.gov/science/objects/milkyway1.html">Milky Way</a> galaxy is about 100,000 light years across.)</p>
<p>This distance limit, combined with the sky area we know the FRB came from (an area half a square degree - or roughly two full Moons across) enormously narrows down the search volume to look for the host galaxy.</p>
<h2>Closing in</h2>
<p>A region of the sky this size typically contains hundreds of galaxies. We used giant optical telescopes in Chile – including the appropriately named Very Large Telescope and Gemini South – to derive distances to these galaxies by either measuring their redshifts directly, or by using their optical colours to estimate their distance.</p>
<p>This allowed us to drastically reduce the number of possible galaxies within the distance limit to just 16. </p>
<p>By far the closest, and we believe most likely to host the FRB, is a nearby spiral galaxy called ESO 601-G036. This is 120 million light years away – making this FRB host almost our next door neighbour.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/242655/original/file-20181029-7056-fvend1.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/242655/original/file-20181029-7056-fvend1.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/242655/original/file-20181029-7056-fvend1.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=599&fit=crop&dpr=1 600w, https://images.theconversation.com/files/242655/original/file-20181029-7056-fvend1.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=599&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/242655/original/file-20181029-7056-fvend1.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=599&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/242655/original/file-20181029-7056-fvend1.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=753&fit=crop&dpr=1 754w, https://images.theconversation.com/files/242655/original/file-20181029-7056-fvend1.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=753&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/242655/original/file-20181029-7056-fvend1.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=753&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Optical image of the search area from the Digitized Sky Survey (DSS). The circles mark possible host galaxies for FRB 171020, but these are all much further away than the most likely galaxy ESO 601-G036, shown in the lower left as a three-colour image from the VLT Survey Telescope (VST) ATLAS survey.</span>
<span class="attribution"><span class="source">ESO, Digitized Sky Survey and VST-ATLAS</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>What is particularly striking about this galaxy is that it shares many similar features to the only galaxy known to produce FRBs: <a href="https://www.sciencealert.com/frb-121102-fast-radio-burst-massive-black-hole-nebula-icrar">FRB 121102</a>.</p>
<p>This FRB is also known as the repeating FRB due to its – so far unique – property of producing multiple bursts. This helped astronomers locate it to a small galaxy about more than 3 billion light years away. </p>
<p>ESO 601-G036 is similar in size, and forming new stars at about the same rate, as the host galaxy of the repeating FRB. </p>
<p>But there is one intriguing feature of the repeating FRB that we don’t see in ESO 601-G036. </p>
<h2>Other emissions</h2>
<p>In addition to repeat bursts of radio emission, the repeating FRB emits lower energy radio emission continuously. </p>
<p>Using CSIRO’s Australia Telescope Compact Array (<a href="https://www.csiro.au/en/Research/Facilities/ATNF/Australia-Telescope-Compact-Array/About-Australia-Telescope-Compact-Array">ATCA</a>) in Narrabri, NSW, we have searched for this persistent radio emission in ESO 601-G036. If it was anything like the repeater’s galaxy, it should have a boomingly bright radio source in it. We saw nothing. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/242662/original/file-20181029-7053-1krmlej.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/242662/original/file-20181029-7053-1krmlej.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/242662/original/file-20181029-7053-1krmlej.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/242662/original/file-20181029-7053-1krmlej.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/242662/original/file-20181029-7053-1krmlej.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/242662/original/file-20181029-7053-1krmlej.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/242662/original/file-20181029-7053-1krmlej.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/242662/original/file-20181029-7053-1krmlej.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The Australia Telescope Compact Array (ATCA) used in the follow-up observations.</span>
<span class="attribution"><span class="source">CSIRO</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Not only did we find that ESO 601-G036 doesn’t have any persistent radio emission, but there are no other galaxies in our search volume that show similar properties to that seen in the repeating FRB. </p>
<p>This points to the possibility that there are different types of fast radio bursts that may even have different origins. </p>
<p>Finding the galaxies that FRBs originate from is a big step towards solving the mystery of what produces these extreme bursts. Most FRBs travel much further distances so finding one so close to Earth allows us to study the environments of FRBs in unprecedented detail. </p>
<h2>The hunt for more</h2>
<p>Unfortunately, we can’t say with absolute certainty that ESO 601-G036 is the galaxy that FRB 171020 came from.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/a-goblin-could-guide-us-to-a-mystery-planet-thought-to-exist-in-the-solar-system-104325">A Goblin could guide us to a mystery planet thought to exist in the Solar system</a>
</strong>
</em>
</p>
<hr>
<p>The next big hurdle in understanding what causes FRBs is to pinpoint more of them. If we can do that we’ll be able to work out not only exactly which galaxy an FRB occurred in, but even where within the galaxy it occurred.</p>
<p>If FRBs occur within the central nuclei of galaxies, this could perhaps point to black holes as their source. Or do they prefer the outskirts of galaxies? Or regions where a lot of new stars have recently formed? There are still so many unknowns about FRBs. </p>
<p>Several radio telescopes around the world are commissioning systems to pinpoint bursts. Our study has shown that by combining observations from radio and optical telescopes we’ll be able to paint a complete picture of FRB host galaxies, and be able to finally determine what causes these FRBs.</p><img src="https://counter.theconversation.com/content/105735/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Elizabeth Mahony does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>
Astronomers think they’ve identified which galaxy was the source of a blast radio energy, over in a fraction of a second. And it’s much closer to us than the others detected, so far.
Elizabeth Mahony, Research Scientist, CSIRO
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/104488
2018-10-10T18:38:07Z
2018-10-10T18:38:07Z
More ‘bright’ fast radio bursts revealed, but where do they all come from?
<figure><img src="https://images.theconversation.com/files/239726/original/file-20181008-72103-uxpt3w.png?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Central antennas of the Australia Square Kilometre Array Pathfinder.</span> <span class="attribution"><span class="source">Alex Cherney/CSIRO</span>, <span class="license">Author provided</span></span></figcaption></figure><p>Fast radio bursts (<a href="https://theconversation.com/au/topics/fast-radio-bursts-6352">FRBs</a>) are one of the great astrophysical mysteries. They are brief, bright flashes of radio waves that last a few milliseconds. Despite happening frequently – thousands occur over the entire sky every day – only a couple dozen have ever been seen.</p>
<p>But we’ve found 20 more bursts, averaging one for every 14 days of observing, with the results <a href="http://dx.doi.org/10.1038/s41586-018-0588-y">published in Nature today</a>.</p>
<p>There are two main reasons why astronomers like me are really excited by FRBs. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/askap-telescope-speeds-up-the-hunt-for-new-fast-radio-bursts-77481">ASKAP telescope speeds up the hunt for new Fast Radio Bursts</a>
</strong>
</em>
</p>
<hr>
<p>First, they represent a new, very unusual, unexpected phenomenon. The bursts come from other galaxies, meaning incredible amounts of energy are required to produce them – some bursts contain more energy than our Sun produces in decades. </p>
<p>Second, FRBs have the potential to be a new tool that we can use to understand the structure of matter in the universe.</p>
<p>The key property of the bursts that could turn them into a valuable tool is their dispersion: shorter (bluer) wavelength radio waves arrive at the telescope before the longer (redder) ones. </p>
<p>This dispersion is the result the radio waves passing through hot gas (plasma), which slows down the radio waves by an amount that depends on the wavelength. The amount of dispersion tells us how much matter the bursts have travelled through, and until now it has been unclear where that matter is. </p>
<figure>
<iframe src="https://player.vimeo.com/video/293891308" width="500" height="281" frameborder="0" webkitallowfullscreen="" mozallowfullscreen="" allowfullscreen=""></iframe>
<figcaption><span class="caption">An FRB’s journey to Earth.</span></figcaption>
</figure>
<p>A fast radio burst leaves a distant galaxy (see the video above), travelling to Earth over billions of years and occasionally passing through clouds of gas in its path. Each time a cloud of gas is encountered, the different wavelengths that make up a burst are slowed by different amounts. </p>
<p>Timing the arrival of the different wavelengths at a radio telescope tells us how much material the burst has travelled through on its way to Earth and allows astronomers to to detect “missing” matter located in the space between galaxies.</p>
<h2>Location, location, location</h2>
<p>There are two places where this matter could be. It could be in the FRB host galaxy, in this case FRBs would be coming from relatively close galaxies. </p>
<p>The other, exciting possibility is that the dispersion is the result of matter in between galaxies. This matter, referred to as the cosmic web, is nearly impossible to study any other way.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/239606/original/file-20181007-72103-1792641.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/239606/original/file-20181007-72103-1792641.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/239606/original/file-20181007-72103-1792641.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=491&fit=crop&dpr=1 600w, https://images.theconversation.com/files/239606/original/file-20181007-72103-1792641.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=491&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/239606/original/file-20181007-72103-1792641.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=491&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/239606/original/file-20181007-72103-1792641.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=617&fit=crop&dpr=1 754w, https://images.theconversation.com/files/239606/original/file-20181007-72103-1792641.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=617&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/239606/original/file-20181007-72103-1792641.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=617&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Cosmic web simulation. Galaxies and clusters of galaxies reside on filaments, which are separated by almost empty regions called voids. Surrounding the filaments is diffuse gas that can be probed by fast radio bursts.</span>
<span class="attribution"><span class="source">NASA, ESA, and E Hallman (University of Colorado, Boulder)</span></span>
</figcaption>
</figure>
<p>Figuring out where it resides is another outstanding problem in astronomy. In this case, the FRBs would be coming from more distant objects. </p>
<p><a href="https://astronomy.curtin.edu.au/research/craft/">Our collaboration</a> decided the first step to solve the FRB mystery was to find more of them, and find them quickly.</p>
<p>To do this we decided to go wide and simultaneously stare at as much sky as possible. We used the Australian Square Kilometre Array Pathfinder (<a href="https://www.atnf.csiro.au/projects/askap/index.html">ASKAP</a>), a radio telescope in regional Western Australia that consists of 36, 12-metre dish antennas.</p>
<p>Each antenna is equipped with phased array feeds – radio cameras that would enable searches 36 times wider than could be seen with older technology.</p>
<p>We further widened the searches by pointing the antennas in different directions like a fly’s eye. While these searches would be less sensitive than those that found bursts previously, mostly with the 64-metre Parkes radio telescope in New South Wales, we were relatively confident bright ones existed in sufficient numbers that we should find more. </p>
<p>To conduct the searches, we used six to nine of the ASKAP antennas, while the rest were used for other observing projects. Our first discovery came after just over three days of observing, as <a href="https://theconversation.com/askap-telescope-speeds-up-the-hunt-for-new-fast-radio-bursts-77481">mentioned earlier in The Conversation</a>.</p>
<p>It turns out that we were a bit lucky to find the first one as soon as we did. I was responsible for scheduling the observing, which could run 24/7, and searching the data. </p>
<p>It was an exciting time, and I was very happy to be on the front line and be the first one to spot a new burst. Over the course of the next year, we found the 19 additional bursts reported.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/239602/original/file-20181007-72103-1etdky6.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/239602/original/file-20181007-72103-1etdky6.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/239602/original/file-20181007-72103-1etdky6.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=682&fit=crop&dpr=1 600w, https://images.theconversation.com/files/239602/original/file-20181007-72103-1etdky6.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=682&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/239602/original/file-20181007-72103-1etdky6.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=682&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/239602/original/file-20181007-72103-1etdky6.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=857&fit=crop&dpr=1 754w, https://images.theconversation.com/files/239602/original/file-20181007-72103-1etdky6.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=857&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/239602/original/file-20181007-72103-1etdky6.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=857&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The ASKAP FRB sample. For each burst, the top panels show what the FRB signal looks like when averaged over all frequencies. The bottom panels show how the brightness of the burst changes with frequency. The bursts are vertical because they have been corrected for dispersion.</span>
<span class="attribution"><span class="source">Ryan Shannon and the CRAFT collaboration</span></span>
</figcaption>
</figure>
<h2>Not the usual FRB</h2>
<p>As the burst count started to rise, we noticed differences with the previously detected ones. The ASKAP bursts have less dispersion than the ones found at Parkes. </p>
<p>This, combined with the fact that the ASKAP bursts are much brighter, indicates that there is a correlation between burst brightness and dispersion. If all the dispersion was coming from within host galaxies, this would not be the case. </p>
<p>We were now able to confidently say that the bursts are experiencing the effects of the diffuse matter in the cosmic web. It also says that bursts are coming from vast distances – from galaxies half way across the universe.</p>
<p>A second key result of our survey is that none of the bursts repeated. As part of our searches, we observed the same regions of sky almost daily, and in total we had spent 12,000 hours (500 days) staring at the positions where we found FRBs.</p>
<p>This makes the bursts different than the best studied, known as <a href="https://www.seti.org/frb-121102-radio-calling-cards-distant-civilization">FRB 121102</a> – aptly called “the repeater” – from which hundreds of pulses have been detected.</p>
<p>Are there two classes of FRBs? It can be scientifically fraught to subdivide phenomena such as FRBs into sub-classes when so few are known. But the differences between the repeater and the rest of the FRBs are starting to become too big to ignore.</p>
<h2>On closer inspection</h2>
<p>The next step for our project is to commission a mode for ASKAP that can be used to localise bursts.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/how-we-found-the-source-of-the-mystery-signals-at-the-dish-41523">How we found the source of the mystery signals at The Dish</a>
</strong>
</em>
</p>
<hr>
<p>Instead of using the fly’s eye approach, we’ll point all of the antennas in the same direction, search for bursts in real time, and then make an image of the sky for the millisecond the FRB emission was passing by Earth.</p>
<p>We’ll be able tie bursts to host galaxies and accurately measure their distances. By combining the distances with the dispersions we’ll be able to start making a 3D map of the cosmic web. </p>
<figure>
<iframe src="https://player.vimeo.com/video/293893521" width="500" height="281" frameborder="0" webkitallowfullscreen="" mozallowfullscreen="" allowfullscreen=""></iframe>
<figcaption><span class="caption">Keith Bannister, Jean-Pierre Macquart, and Ryan Shannon describe their work on fast radio bursts (FRBs) and the telescope used for their discovery. Credit: CSIRO.</span></figcaption>
</figure><img src="https://counter.theconversation.com/content/104488/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Ryan Shannon receives funding from the Australian Research Council (ARC) and is a member of the ARC Centre of Excellence for Gravitational-Wave Discovery (OzGrav).</span></em></p>
We still don’t know what causes these mysterious Fast Radio Bursts deep in the universe, but we’ve detected a whole new batch of them.
Ryan Shannon, Postdoctoral fellow, Swinburne University of Technology, Swinburne University of Technology
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/101607
2018-08-17T11:08:18Z
2018-08-17T11:08:18Z
New telescope chases the mysteries of radio flashes and dark energy
<figure><img src="https://images.theconversation.com/files/232250/original/file-20180816-2897-1biximd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">HIRAX prototype dishes at Hartebeesthoek Astronomy Observatory near Johannesburg.</span> <span class="attribution"><span class="source">Kabelo Kesebonye</span></span></figcaption></figure><p><em>South Africa is becoming one of the world’s most important radio astronomy hubs, thanks in large part to its role as co-host of the Square Kilometre Array (SKA). Now a new telescope is being unveiled that will be built at the SKA South Africa site in the Karoo. The Hydrogen Intensity and Real-time Analysis eXperiment (HIRAX) <a href="https://bit.ly/2nQdyQT">project</a> is an international collaboration being led by scientists from the University of KwaZulu-Natal. The Conversation Africa chatted to project leader Professor Kavilan Moodley about HIRAX’s scientific goals.</em></p>
<p><strong>What will HIRAX do, and how?</strong></p>
<p>It’s an <a href="http://astronomy.swin.edu.au/cosmos/R/Radio+Interferometer">interferometer array</a> that will be made up of 1024 6-metre dishes. Interferometer arrays are really cool because they combine signals from many telescopes to provide the resolution of a larger telescope. </p>
<p><a href="https://acru.ukzn.ac.za/hirax-postdocs-ad/">HIRAX</a> has two main science goals: to study the evolution of dark energy by tracking neutral hydrogen gas in galaxies, and to detect and localise mysterious radio flashes called fast radio bursts.</p>
<p>Dark energy is a mysterious force driving the accelerated expansion of our universe. HIRAX can study it using a unique cosmic ruler provided by nature, called <a href="http://astronomy.swin.edu.au/cosmos/B/Baryonic+Acoustic+Oscillations">baryon acoustic oscillations</a>. These were generated in the very early universe, which was a hot and dense soup of particles and light. Small irregularities gave rise to sound waves in this primordial soup. </p>
<p>These waves carried matter as they travelled until a time when matter and light separated, distributing matter in a very characteristic pattern. Neutral hydrogen gas is a great tracer of the universe’s matter distribution. This neutral hydrogen emits a signal at 1420 MHz, which is in the range of frequencies used by cellular networks and UHF television channels; the signal gets stretched to lower frequencies as the universe expands.</p>
<p>HIRAX will operate between 400 and 800 MHz allowing it to map neutral hydrogen in the universe between 7 to 11 billion years ago. Studying the characteristics of dark energy during this time has the potential to unravel its properties, as this is a vital time when dark energy became the primary component in the universe and accelerated its expansion.</p>
<p>The second focus area involves mysterious bright, millisecond flashes that scientists call fast radio bursts. Scientists do not know what causes these. They’re also hard to detect and localise since they’re so brief and most telescopes only observe a small region of the sky. </p>
<p>HIRAX’s large field of view will allow it to observe large portions of sky daily – so when the flashes happen, the instrument will be more likely to see them. We expect that it’ll see up to a dozen of these flashes a day; to put that in perspective, only a few dozen in total have ever been observed.</p>
<p>And HIRAX will add the unique capability of being able to figure out exactly where in the sky these fast radio bursts occur, by working with several other Southern African countries to build 8-dish outrigger arrays. These, in combination with the main array, will help localise these bursts to within their hosting galaxies. </p>
<p><strong>It sounds like HIRAX will be collecting huge amounts of data?</strong></p>
<p>It will need to collect large amounts of data at a rate of around 6.5 Terabits per second. That’s comparable to <a href="http://www.africabandwidthmaps.com/">all of Africa’s international bandwidth</a>. For that, HIRAX needs to design and manufacture high precision dishes, receivers and other instrumentation; we’re working with local companies on this challenge.</p>
<p>Then the team will need to figure out smart ways to compress, store and analyse this data. That will require big data hardware and software. </p>
<p>We hope that the design and manufacturing abilities required to equip HIRAX properly will open up many opportunities for local industries in the region around the SKA project. </p>
<p><strong>Is this an SKA project, or entirely separate but using space and technology at the SKA?</strong></p>
<p>The project originated as a response by UKZN and its partner institutions to a call for institutional flagship projects by the National Research Foundation. So it’s independent from the SKA and its precursor, the MeerKAT – but will benefit greatly from the South African investment in the SKA project, which gives it access to excellent infrastructure hosted by the <a href="http://www.ska.ac.za/about/sarao/">South African Radio Astronomy Observatory</a>. </p>
<p>By sharing a location with MeerKAT on the SKA South Africa site, HIRAX will be able to conduct science in “radio-clear” skies across its wide frequency range; <a href="http://www.ska.ac.za/about/astronomy-geographic-advantage-act/">legislation</a> has been introduced to limit radio frequency interference on the SKA SA site. It’s also a great space because it allows access to the southern sky covered by other cosmological surveys and, in turn, more of the galaxy where we’ll find pulsars.</p>
<p>Being part of the “Karoo radio park” will allow HIRAX to add to South Africa’s radio astronomy engineering and infrastructure. This infrastructure and the resulting science will increase South Africa’s reputation as a global leader in radio astronomy. </p>
<p>HIRAX will also contribute to training the next generation of scientists for the SKA; students working on the project will be trained in all aspects of the telescope, from engineering to science. Students who build hardware are also involved in data analysis, which provides a special environment for training upcoming radio astronomy experts.</p>
<p>Finally, there are strong scientific synergies with MeerKAT (which was <a href="http://www.ska.ac.za/media-releases/meerkat-radio-telescope-inaugurated-in-south-africa-reveals-clearest-view-yet-of-center-of-the-milky-way/">officially launched</a> in July 2018). If HIRAX discovers any interesting new pulsars, for instance, MeerKAT can conduct follow-up timing observations at higher frequencies. </p>
<p><em>This article by co-authored by Carolyn Crichton, a technical writer with the HIRAX Project. Before joining the project, she worked for five years at NASA’s Goddard Space Flight Center in the US.</em></p><img src="https://counter.theconversation.com/content/101607/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Kavilan Moodley receives funding from the University of KwaZulu-Natal and the National Research Foundation.
The HIRAX project receives funding from the University of KwaZulu-Natal and the Department of Science and Technology via the National Research Foundation.</span></em></p>
By sharing a location with the SKA, HIRAX will be able to conduct science in “radio-clear” skies across its wide frequency range.
Kavilan Moodley, Associate Professor, University of KwaZulu-Natal
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/77481
2017-05-22T19:58:13Z
2017-05-22T19:58:13Z
ASKAP telescope speeds up the hunt for new Fast Radio Bursts
<figure><img src="https://images.theconversation.com/files/170086/original/file-20170519-12231-tzggyf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">ASKAP at night.</span> <span class="attribution"><span class="source"> Alex Cherney/terrastro.com</span>, <span class="license">Author provided</span></span></figcaption></figure><p>They’re mysterious bursts of radio waves from space that are over in a fraction of a second. Fast Radio Bursts (<a href="https://theconversation.com/au/topics/fast-radio-bursts-6352">FRBs</a>) are thought to occur many thousands of times a day, but since their <a href="http://science.sciencemag.org/content/318/5851/777.full">first detection</a> by the Parkes radio telescope a decade ago only 30 have been observed.</p>
<p>But once the Australian Square Kilometre Array Pathfinder (<a href="https://www.csiro.au/en/Research/Facilities/ATNF/ASKAP">ASKAP</a>) joined the hunt we had our first new FRB after just three and half days of observing. This was soon followed by a further two FRBs. And the telescope is not even fully operational yet.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/168889/original/file-20170511-32610-197o80x.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/168889/original/file-20170511-32610-197o80x.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/168889/original/file-20170511-32610-197o80x.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=867&fit=crop&dpr=1 600w, https://images.theconversation.com/files/168889/original/file-20170511-32610-197o80x.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=867&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/168889/original/file-20170511-32610-197o80x.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=867&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/168889/original/file-20170511-32610-197o80x.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1089&fit=crop&dpr=1 754w, https://images.theconversation.com/files/168889/original/file-20170511-32610-197o80x.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1089&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/168889/original/file-20170511-32610-197o80x.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1089&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The first FRB that ASKAP found. Bottom panel shows a grey scale image of what the FRB looks like. It’s less than 1 millisecond long and we detect it over a range of frequencies from 1,100 MHz to 1,400 MHz. The top panel shows what the FRB looks like when you add up all the frequency channels.</span>
<span class="attribution"><span class="source">Ryan Shannon (CSIRO/Curtin University)</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>The fact that ASKAP detects FRBs so readily means it is now poised to tackle the big questions. </p>
<p>One of these is what causes an FRB in the first place. They are variously attributed by hard-nosed and self-respecting physicists to everything from <a href="https://theconversation.com/how-we-found-the-source-of-the-mystery-signals-at-the-dish-41523">microwave ovens</a>, to the accidental <a href="https://www.newscientist.com/article/2124209-could-fast-radio-bursts-really-be-powering-alien-space-ships/">transmissions of extraterrestrials</a> making their first baby steps in interstellar exploration. </p>
<p>The astounding properties of these FRBs have so enthralled astronomers that, in the decade since their discovery, there are more theories than observed bursts.</p>
<h2>A distant flash</h2>
<p>FRBs are remarkable because they are outrageously bright in the radio spectrum yet appear extremely distant. As far as astronomers can tell, they come from a long way away - halfway across the observable universe or more. Because of that, whatever makes FRBs must be pretty special, unlike anything astronomers have ever seen. </p>
<p>What has astronomers really excited is the fossil record imprinted on each burst by the matter it encounters during its multibillion-year crossing of the universe. </p>
<p>Matter in space exerts a tiny amount drag on the radio waves as they hurtle across the universe, like the air drags on a fast-moving plane. But here’s the handy bit: the longer the radio waves, the more the drag. </p>
<p>By the time the radio waves arrive at our telescopes, the shorter waves arrive just before the longer ones. By measuring the time delay between the short waves and the longer ones, astronomers can work out how much matter a given burst has travelled through on its journey from whatever made it, to our telescope.</p>
<p>If we can find enough bursts, we can work out how much ordinary matter - the stuff you and I and all visible matter is made of - exists in the universe, and tally up its mass.</p>
<p>The best guess so far is that we are missing roughly half of all the normal matter, with the rest lying in the vast voids between the galaxies — the very regions so readily probed by FRBs.</p>
<p>Are FRBs the weigh stations of the cosmos?</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/xObKVJrnxZg?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
</figure>
<h2>Difficult to find and harder to pinpoint</h2>
<p>There are a few reasons why we still have so many questions about FRBs. First, they are tricky to find. It takes the Parkes telescope around two weeks of constant watching to find a burst. </p>
<p>Worse, even when you’ve found one, many radio telescopes like Parkes can only pinpoint its location in the sky to a region about the size of the full Moon. If you want to work out which galaxy an FRB came from, you have hundreds to choose from within that area. </p>
<p>The ideal FRB detector needs both a large field of view and the ability to pinpoint events to a region one thousandth the area of the Moon. Until recently, no such radio telescope existed.</p>
<h2>A jewel in the desert</h2>
<p>Now it does in ASKAP, a radio telescope being built by the CSIRO in Murchison Shire, 370km northeast of Geraldton in Western Australia. It’s actually a network of 36 antennas, each 12 metres in diameter.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/168893/original/file-20170511-32620-1umkqxp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/168893/original/file-20170511-32620-1umkqxp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/168893/original/file-20170511-32620-1umkqxp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=291&fit=crop&dpr=1 600w, https://images.theconversation.com/files/168893/original/file-20170511-32620-1umkqxp.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=291&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/168893/original/file-20170511-32620-1umkqxp.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=291&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/168893/original/file-20170511-32620-1umkqxp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=366&fit=crop&dpr=1 754w, https://images.theconversation.com/files/168893/original/file-20170511-32620-1umkqxp.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=366&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/168893/original/file-20170511-32620-1umkqxp.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=366&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">ASKAP antennas during fly’s-eye observing. All the antennas point in different directions.</span>
<span class="attribution"><span class="source">Kim Steele (Curtin University)</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>ASKAP is a very special machine, because each antenna is equipped with an innovative CSIRO-designed receiver called a phased-array feed. While most radio telescopes see just one patch of sky at time, ASKAP’s phased-array feeds see 36 different patches of sky simultaneously. This is great for finding FRBs because the more sky you can see, the better chance you have of finding them.</p>
<p>To find lots of FRBs we need to cast an even wider net. Normally, ASKAP dishes all point in the same direction. This is great if you’re making images or want to find faint FRBs.</p>
<p>Thanks to <a href="http://science.sciencemag.org/content/354/6317/1249">recent evidence from Parkes</a>, we realised there might be some super-bright FRBs too. </p>
<p>So we took a hint from nature. In the same way that the segments of a fly’s eye allow it to see all around it, we pointed all our antennas in lots of different directions. This fly’s-eye observing mode enabled us to see a total patch of sky about the size of 1,000 full Moons.</p>
<p>That’s how we discovered this new FRB within days of starting, and using just eight of ASKAP’s total of 36 antennas.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/170257/original/file-20170522-12231-19sr7rj.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/170257/original/file-20170522-12231-19sr7rj.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/170257/original/file-20170522-12231-19sr7rj.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=575&fit=crop&dpr=1 600w, https://images.theconversation.com/files/170257/original/file-20170522-12231-19sr7rj.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=575&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/170257/original/file-20170522-12231-19sr7rj.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=575&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/170257/original/file-20170522-12231-19sr7rj.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=723&fit=crop&dpr=1 754w, https://images.theconversation.com/files/170257/original/file-20170522-12231-19sr7rj.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=723&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/170257/original/file-20170522-12231-19sr7rj.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=723&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Radio image of the sky where ASKAP found its first FRB. The blue circles are the 36 patches of the sky that ASKAP antenna number 5 (named <em>Gagurla</em> in the local Wadjarri language) was watching at the time the FRB was detected. The red smudge marks where the FRB came from. The black dots are galaxies, far, far, away. The full Moon is shown to scale, in the bottom corner.</span>
<span class="attribution"><span class="source">Ian Heywood (CSIRO)</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<h2>When fully operational</h2>
<p>So far, in fly’s-eye mode we have made no attempt to combine the signals from all the antennas. ASKAP’s real party piece will be to point all the telescopes in the same direction and combine the signals from all the antennas.</p>
<p>This will give us a precise position for every single burst, enabling us to identify the host galaxy of each FRB and measure its exact distance.</p>
<p>Armed with this information, we will be able to activate our network of cosmic weigh stations. At this point we will be able to investigate a fundamental question that has been plaguing astronomers for more than 20 years: where is the missing matter in the universe?</p><img src="https://counter.theconversation.com/content/77481/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Keith Bannister works for the CSIRO.</span></em></p><p class="fine-print"><em><span>Jean-Pierre Macquart receives funding from the Australian Research Council and is a member of the ARC Centre of Excellence for All-sky Astrophysics. </span></em></p>
It used to take weeks to find any of these mysterious signals from deep in space but when the new telescope started looking it found one within days. Then another.
Keith Bannister, Astronomer, CSIRO
Jean-Pierre Macquart, Senior Lecturer in Astrophysics, Curtin University
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/55965
2016-03-09T17:07:28Z
2016-03-09T17:07:28Z
Message from aliens or colliding objects? The hunt for enigmatic radio bursts is about to get real
<figure><img src="https://images.theconversation.com/files/114428/original/image-20160309-13722-6l6j3v.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Artist's impressiong of the Square Kilometre Array, which will revolutionise our ability to detect fast radio bursts.</span> <span class="attribution"><span class="source">SKA Project Development Office and Swinburne Astronomy Productions - Swinburne Astronomy Productions for SKA Project Development Office</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span></figcaption></figure><p>Astronomers are getting ever closer to understanding the origin of mysterious “fast radio bursts” – very brief but intense pulses of radio waves from outer space – after a series of <a href="https://www.washingtonpost.com/news/speaking-of-science/wp/2016/03/02/new-paper-adds-a-surprising-twist-to-the-cosmic-hunt-for-fast-radio-bursts/">recent contradictory findings</a>. While the cause of these powerful blips is still unknown, scientists’ eagerness to find out is driving a renaissance in radio astronomy. Along with a revolution in our ability to map huge chunks of the sky in real time over the coming decade, this means the hunt for an answer is starting to look promising.</p>
<p>The first discovery of a fast radio burst, lasting only 5 milliseconds, <a href="http://science.sciencemag.org/content/318/5851/777">was announced in 2007</a> by scientists mining data from Australia’s <a href="http://www.parkes.atnf.csiro.au/">Parkes radio telescope</a>. Unfortunately, the burst did not repeat, so it couldn’t be independently confirmed by others. Several years passed before new bursts <a href="http://iopscience.iop.org/article/10.1088/0004-637X/790/2/101/meta">were found</a> at different locations in the sky using independent telescopes in <a href="https://www.naic.edu/">Arecibo, Puerto Rico </a>and <a href="https://science.nrao.edu/facilities/gbt">Greenbank, US</a>. </p>
<figure class="align-right ">
<img alt="" src="https://images.theconversation.com/files/114431/original/image-20160309-13730-14j68od.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/114431/original/image-20160309-13730-14j68od.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=749&fit=crop&dpr=1 600w, https://images.theconversation.com/files/114431/original/image-20160309-13730-14j68od.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=749&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/114431/original/image-20160309-13730-14j68od.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=749&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/114431/original/image-20160309-13730-14j68od.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=941&fit=crop&dpr=1 754w, https://images.theconversation.com/files/114431/original/image-20160309-13730-14j68od.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=941&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/114431/original/image-20160309-13730-14j68od.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=941&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Parkes telescope.</span>
<span class="attribution"><span class="source">CSIRO</span>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>But astronomers failed to agree on what had caused the bursts. As they had been one-off blips, more like whistlers than repeating signals, it was suggested that they could come from catastrophic one-off events – such as a <a href="http://nature.com/articles/doi:10.1038/nature17140">neutron star colliding with a black hole</a>. Other explanations included <a href="http://www.isciencetimes.com/articles/6529/20131216/fast-radio-bursts-originate-nearby-milky-way-galaxy.htm">huge flashes of brightness</a>, similar to solar flares, from stars in our own galaxy, or simply <a href="http://www.nature.com/news/microwave-oven-blamed-for-radio-telescope-signals-1.17510">contaminating signals</a> from radio waves emitted on Earth. Some even speculated that the signals could be <a href="https://www.newscientist.com/article/mg22630153-600-is-this-et-mystery-of-strange-radio-bursts-from-space/">transmitted by distant alien civilisations</a>. </p>
<h2>Bewildering results</h2>
<p>On March 2, it seemed the mystery had finally been solved when scientists <a href="http://nature.com/articles/doi:10.1038/nature17140">announced</a> the detection of what they interpreted to be an afterglow – lasting six days – from a fast radio burst. For the first time, they were able to suggest the galaxy that the burst could have come from, roughly 6 billion light years from Earth. The researchers suggested it likely originated when two compact objects such as a neutron star and a black hole collided. </p>
<p>But astronomers’ excitement was short-lived. Just days later, <a href="http://arxiv.org/pdf/1602.08434v1.pdf">new observations from the Very Large Array</a> suggested these findings could be flawed. The array had seen the signal get stronger rather than fade, which would have been expected for an afterglow. The researchers therefore concluded it was not an afterglow from a fast radio burst at all, but rather radiation from a supermassive black hole at the heart of the galaxy gradually devouring material from its surroundings. This is a common phenomenon; even the centres of <a href="http://iopscience.iop.org/article/10.1088/0004-637X/703/1/802/meta">nearby galaxies show variable radio brightness</a>.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/114427/original/image-20160309-13709-enc8f3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/114427/original/image-20160309-13709-enc8f3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=475&fit=crop&dpr=1 600w, https://images.theconversation.com/files/114427/original/image-20160309-13709-enc8f3.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=475&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/114427/original/image-20160309-13709-enc8f3.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=475&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/114427/original/image-20160309-13709-enc8f3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=597&fit=crop&dpr=1 754w, https://images.theconversation.com/files/114427/original/image-20160309-13709-enc8f3.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=597&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/114427/original/image-20160309-13709-enc8f3.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=597&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Arecibo Observatory.</span>
<span class="attribution"><span class="source">H. Schweiker/WIYN and NOAO/AURA/NSF.</span></span>
</figcaption>
</figure>
<p>To make matters even more confusing, astronomers using the Arecibo radio telescope have just announced the discovery of a collection of signals which they argue <a href="http://www.independent.co.uk/news/science/fast-radio-bursts-scientists-hear-huge-mysterious-signal-from-deep-in-space-a6909211.html">could be a repeating</a> fast radio burst. This is a huge surprise as we had until now assumed that the bursts were one-off events. These signals are ten times weaker than traditional fast radio bursts and seem to have different properties. There also remains uncertainty about the exact location of each burst on the sky, so they may not be related to one catastrophic event. It is clear that many more fast radio bursts need to be discovered and studied before generalisations about their nature and origin can be made.</p>
<h2>A technological revolution</h2>
<p>Trying to discover a burst and, at exactly the same time, pinpoint accurately where on the sky it comes from is still a major challenge for radio observatories, as their telescopes have relatively small fields of view. This is also challenging for astronomers working at wavelengths other than the radio bands who are searching for <a href="https://theconversation.com/explainer-what-is-the-electromagnetic-spectrum-8046">other kinds of electromagnetic radiation</a> (such as X-rays or the kind of optical light that we can see). Such radiation may have been emitted in the same event that caused the fast radio bursts. If a radio signal could be backed up by discoveries in these other parts of the spectrum, we could measure the distance and understand the physics processes driving these events.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/114434/original/image-20160309-13726-1ieopnr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/114434/original/image-20160309-13726-1ieopnr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/114434/original/image-20160309-13726-1ieopnr.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/114434/original/image-20160309-13726-1ieopnr.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/114434/original/image-20160309-13726-1ieopnr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/114434/original/image-20160309-13726-1ieopnr.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/114434/original/image-20160309-13726-1ieopnr.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Could a supermassive black hole be to blame for the bursts?</span>
<span class="attribution"><span class="source">NASA</span></span>
</figcaption>
</figure>
<p>This problem is not new to astronomers. Intense, short-lived flashes of high-energy gamma rays (radiation that is much more energetic than radio waves) – <a href="http://imagine.gsfc.nasa.gov/science/objects/bursts1.html">discovered by military satellites</a> in the 1960s and named “gamma ray bursts” – remained a mystery until they could be pinpointed in the sky with sufficient accuracy to allow other telescopes (looking in different wavelengths) to help search. Scientists working with different telescopes could ultimately establish that they came from far beyond our own galaxy. A revolution in the understanding of the underlying physics of these bursts came with the launch of NASA’s Swift satellite, which accurately locates new busts and automatically notifies ground-based robotic telescopes in real time <a href="http://www.nature.com/nature/journal/v504/n7478/full/nature12814.html">so they can get a closer look</a>.</p>
<p>At radio wavelengths, new breakthroughs may come from upgrades of existing observatories, but the development of a new global radio facility – the <a href="https://www.skatelescope.org/">Square Kilometer Array </a>(SKA) – in the coming decade is set to revolutionise this field. SKA, a huge network of radio antennas, will combine the ability to see large parts of the sky with fast detection technology to create accurate radio maps of the sky at any given moment. This will give radio astronomers a super all-in-one search and locate machine. It could also deliver news of discoveries in real time to astronomers searching for light at other parts of the spectrum with other facilities, which will see a similar revolution in the ability to scan the sky in real time. </p>
<p>But in the radio bands in particular, it will never be possible to store all of the data collected. Instead, astronomers will have to develop sophisticated hardware and software to sift through the data in real time to capture and identify fleeting events like fast radio bursts. </p>
<p>It may seem like a lot of hurdles to overcome, but it is all happening at a rapid pace. So perhaps sometime in the next decade or two we will know whether “fast radio bursts” are created by aliens or cataclysmic events … or just from microwaves in our kitchens.</p><img src="https://counter.theconversation.com/content/55965/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Carole Mundell receives funding from the Science and Technology Facilities Council, the Royal Society and the Wolfson Foundation. However, the views expressed here are her own and not those of the research council.</span></em></p>
A technological revolution in astronomical observations could be the key to understanding the perplexing phenonenon known as ‘fast radio bursts’ from outer space.
Carole Mundell, Head of Astrophysics, University of Bath
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/41523
2015-05-25T01:55:45Z
2015-05-25T01:55:45Z
How we found the source of the mystery signals at The Dish
<figure><img src="https://images.theconversation.com/files/82365/original/image-20150520-11431-16irdjc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Scientists knew the mystery signals were close by the Parkes radio telescope: but what was the source?</span> <span class="attribution"><a class="source" href="https://www.flickr.com/photos/pikerslanefarm/3447796591/">Flickr/Amanda Slater</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p>Everyone likes solving a mystery, and the hunt for the source of strange signals detected by Australia’s Parkes radio telescope is a classic. Although how “aliens” became involved in the story is more of a media mystery.</p>
<p>But first to those strange signals. A few months ago I wrote about <a href="https://theconversation.com/a-faster-response-needed-to-see-fast-radio-bursts-in-the-universe-36551">searching for fast radio bursts</a> (FRBs). The source of these powerful, millisecond bursts is unknown but we’re getting closer to understanding them.</p>
<p>The first FRB was found in 2007. It actually occurred in 2001, but was discovered six years later during a more close and careful inspection of archival data from the Parkes radio telescope. That same care was applied to other old data sets in the hope that more FRBs waited to be discovered.</p>
<p>As part of her PhD at Swinburne University, Sarah Burke Spolaor looked through other old data sets using similar techniques. Instead of finding undiscovered FRBs, she found these strange new signals that she called perytons. They were like FRBs, but different.</p>
<p>When astronomers look for pulses from astrophysical sources (like <a href="https://theconversation.com/au/topics/pulsars">pulsars</a> or FRBs) we use a few key features to tell the real signals apart from the noise of radio devices on Earth.</p>
<p>First, a pulse that has travelled through space experiences dispersion, meaning that the signal arrives at different times at different wavelengths because of how it travels through interstellar electrons. Since signals from Earth don’t travel through all those electrons, they don’t follow the same wavelength-time relation.</p>
<p>Secondly, we use a receiver on the Parkes telescope that has 13 pixels that each looks at a different place on the sky. A pulse coming from a fixed point in the sky will appear in only one pixel (or a few neighbouring pixels if it is very bright) but signals from Earth will usually appear in all 13 at the same time.</p>
<p>The perytons <a href="http://iopscience.iop.org/0004-637X/727/1/18/">first reported</a> by Burke Spolaor and colleagues in 2011 passed the first test, they had a similar wavelength-time relation as the pulses of interest, but they didn’t pass the second; they were in all 13 beams at once. So the signals had to be coming from Earth, that much was clear. But what could be causing them? (The paper also notes that the name peryton was chosen from mythology to be unassociated with an exact
physical phenomenon, due to the ambiguous origin of the detections. Perytons
are winged elk that cast the shadow of a man.)</p>
<h2>Hunting the local source</h2>
<p>The answer wasn’t immediately obvious, as only about 11 perytons were found, all in old data from 1998 to 2002, making it difficult to trace back the source of the odd pulses.</p>
<p>In their <a href="http://dx.doi.org/10.1088/0004-637X/727/1/18">2011 paper</a>, Burke Spolaor and colleagues suggested possible origins such as lightning, solar bursts or transient events within Earth’s atmosphere, but no conclusive link could be made. <a href="http://dx.doi.org/10.1111/j.1365-2966.2011.20029.x">Further investigation</a> showed the perytons were more likely of human-generated origin.</p>
<p>And so perytons became a sort of troubling mystery. Even with the discovery of more FRBs in the past three years, perytons still lurked in the shadows. Since it has been known from the start that perytons come from a source nearby, they haven’t been an active field of study for radio astronomers. No new leads had come up to hint at where they might be coming from.</p>
<p>Until recently. Earlier this year, we got the breakthrough we needed to solve the peryton mystery once and for all.</p>
<p>Three new perytons were spotted in our data at Parkes during the week of January 19. Each one was discovered within a day of when it happened thanks to advances in data processing used at Parkes.</p>
<p>Speedy software to search for bursts developed by former Swinburne PhD student Ben Barsdell and incorporated into our newest project, the SUrvey for Pulsars and Extragalactic Radio Bursts (<a href="https://sites.google.com/site/publicsuperb/">SUPERB</a>), led to quicker detection. Since we found them in relatively short order, we were able to go back and look at whether anything special was happening on site during that particular week. Astronomers from SUPERB began working with the staff at Parkes to try to hunt down the source of the perytons. </p>
<h2>An important clue</h2>
<p>According to the on-site staff, nothing out of the ordinary was happening that week that might be responsible, but they did provide one more important clue.</p>
<p>In December 2014 CSIRO installed a radio frequency interference (RFI) monitor at the Parkes site to monitor the RFI environment around the telescope. This type of monitoring becomes increasingly important as radio-emitting technologies such as mobile phones, Wi-Fi and digital television encroach on radio telescope sites.</p>
<p>The RFI monitor data, which hadn’t been available for previous peryton discoveries, revealed something important: at the time of each peryton event, there was also a period of radio emission at the frequency 2.5 GHz, out of the range we were observing with the telescope. Whatever was causing the perytons had to be responsible for these spikes, too.</p>
<p>Many consumer electronics emit at 2.5 GHz and the most notorious of these is the <a href="http://hyperphysics.phy-astr.gsu.edu/hbase/waves/mwoven.html">microwave oven</a>. So we began to test the microwave ovens on site (one in the staff kitchen and one in the visitors’ centre) to see if we could make the perytons happen on purpose. Our initial tests of running the microwave oven in a normal mode were unsuccessful and we didn’t see any perytons from either of the microwave ovens.</p>
<p>Finally, on March 17, almost two months after our initial find, we tested the microwave ovens in a slightly unusual way. We tried stopping the microwave oven by opening the door and boom! We saw perytons just like the ones we’d seen before!</p>
<p>We found that we could generate perytons in our data by simply having a direct line of sight between the microwave oven and the telescope receiver (without the telescope surface itself in the way) and stopping the microwave oven by opening the door. Perytons come from microwave ovens! Solved!</p>
<p>From a scientific perspective this work was a satisfying conclusion to months of hard work by a large group of people. But from the media’s perspective this story was apparently too tempting not to spin.</p>
<h2>Who mentioned the aliens?</h2>
<p>Most of the media coverage about this work has centred around “<a href="http://www.theguardian.com/science/2015/may/05/microwave-oven-caused-mystery-signal-plaguing-radio-telescope-for-17-years">baffled scientists</a>” and “<a href="http://metro.co.uk/2015/04/13/alien-signals-from-space-actually-came-from-scientists-microwaves-5147355/">alien signals from space</a>” in a way that makes astronomers sound like puzzled boffins who thought they’d found something Nobel prize-worthy that ended up coming from next door. </p>
<p>Indeed, in some cases it was sufficient to copy and paste a previous headline and article but add the word “aliens” a few more times for good measure. It became clear that the majority of writers had never read <a href="http://arxiv.org/pdf/1504.02165v1.pdf">our paper</a> or taken time to properly represent our science, an unfortunate and frustrating outcome.</p>
<p>Alas we were never looking for extra-terrestrial life, studying alien signals or confusing astronomy with gastronomy. We always knew perytons were coming from nearby; the real fun lay in putting all the pieces together to solve the puzzle. </p>
<p>Even though one radio mystery has been solved another still remains – the source of the fast radio bursts. </p>
<p>We still don’t know exactly what is causing the FRBs that started this whole peryton investigation, although we find that they cannot be explained by the same microwave ovens and many properties of FRBs point towards a genuine astrophysical origin. So the hunt continues.</p><img src="https://counter.theconversation.com/content/41523/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Emily Petroff works for Swinburne University of Technology and is completing a joint PhD with CSIRO Astronomy and Space Science. She is a member of the ARC Centre of Excellence for All-Sky Astrophysics "CAASTRO".</span></em></p>
Astronomers used to probing the universe always knew that strange signals detected by the Parkes radio telescope were coming from somewhere closer to home. But finding the source was the tricky bit.
Emily Petroff, PhD candidate in Astro Physics, Swinburne University of Technology
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/36551
2015-02-05T19:37:12Z
2015-02-05T19:37:12Z
A faster response needed to see Fast Radio Bursts in the universe
<figure><img src="https://images.theconversation.com/files/71133/original/image-20150204-28594-19551o6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A fast radio burst was detected live at Parkes in May 2014.
</span> <span class="attribution"><a class="source" href="https://www.flickr.com/photos/29005492@N07/7589502996">Flickr/Wayne England</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span></figcaption></figure><p>Astronomers are trying to improve their hunt for rapid bursts of radio emission in the universe called Fast Radio Bursts (FRBs) so they can better observe these mysterious events, which are thought to occur thousands of times a day. Only nine have so far been detected.</p>
<p>The most recent burst was spotted in the early hours of the morning on May 15 last year when the <a href="http://www.csiro.au/portals/education/programs/parkes-radio-telescope/about-the-dish">Parkes radio telescope</a>, in New South Wales, was observing a patch of sky in the direction of the Aquarius constellation.</p>
<p>This region was of interest to our team of astronomers because a Fast Radio Burst had been detected emanating from that direction back in 2011. We suspected these bursts might repeat themselves, even years later, so we visited the spot again.</p>
<p>While we didn’t see a repeat of the old burst we did find something interesting. A new burst of radio waves lit up the receiver at preciesly 3:14am.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/71134/original/image-20150204-28612-w9esdt.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/71134/original/image-20150204-28612-w9esdt.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/71134/original/image-20150204-28612-w9esdt.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=254&fit=crop&dpr=1 600w, https://images.theconversation.com/files/71134/original/image-20150204-28612-w9esdt.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=254&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/71134/original/image-20150204-28612-w9esdt.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=254&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/71134/original/image-20150204-28612-w9esdt.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=319&fit=crop&dpr=1 754w, https://images.theconversation.com/files/71134/original/image-20150204-28612-w9esdt.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=319&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/71134/original/image-20150204-28612-w9esdt.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=319&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Live detection of the pulse of a fast radio burst as observed by the Parkes telescope.</span>
<span class="attribution"><span class="source">Emily Petroff</span></span>
</figcaption>
</figure>
<p>Within 10 seconds the detector systems working through the data identified the burst and sent an automated email to the scientists.</p>
<blockquote>
<p>Subject: New Detection: FRB 140514.</p>
</blockquote>
<p>The Parkes team sprang into action within minutes of getting the message and began emailing collaborators around the world. Coordinates were sent, telescopes were pointed, and the first multi-wavelength follow-up of a Fast Radio Burst discovery was underway. </p>
<p>In the days, weeks and months that followed, the location of FRB 140514 was observed with telescopes around the world and in space looking for any changes in the field that might give away where exactly the burst came from.</p>
<p>Unfortunately, these telescopes found nothing that could pinpoint the source or shed definitive light on its origin.</p>
<p>Clearly astronomers need to respond as quickly as possible when a radio burst is found if we are to better understand these curious phenomena and their causes.</p>
<h2>Fast Radio Burst origins</h2>
<p>Fast Radio Bursts first attracted the attention of the astronomical community when the first event was <a href="http://www.sciencemag.org/content/318/5851/777.abstract">discovered in 2007</a> (in archival data recorded in 2001).</p>
<p>Since then, only nine more bursts have been found including the one picked up last year by the CSIRO’s Parkes radio telescope.</p>
<p>At the moment we don’t know for certain what is causing these <a href="https://theconversation.com/fast-radio-bursts-new-intergalactic-messengers-15700">mysterious bursts</a> that we’re so eager to find.</p>
<p>Since these flashes occur on millisecond timescales, whatever it is has to be very bright, and very short-lived. Current contenders are things like giant flares from energetic stars called <a href="https://theconversation.com/a-rare-magnetic-star-is-born-with-a-push-in-the-right-direction-26510">magnetars</a> or the collapse of a neutron star to form a black hole.</p>
<p>In either case, the sources are believed to be billions of light years away, in galaxies spread out across the universe.</p>
<p>How do we know they originate so far away from us? Astronomers have been using radio pulses to study the space between stars for years. The vacuum of space is not quite empty and contains a small number of particles per cubic metre.</p>
<p>Radio pulses travelling through this medium encode information about how many particles they have encountered on their way from a source to our telescope. This gives us a measure of the average density of the space between stars, or the interstellar medium. </p>
<p>Fast Radio Bursts appear to have travelled through about ten times more particles than we expect from the Milky Way. To account for all those particles, the burst must have also travelled through the intergalactic medium as well, putting their sources billions of light years distant.</p>
<p>If the exact distance to a burst could be measured with an optical telescope, the information from these bursts could be used to determine the “weight” of the universe in a particular direction, something that has never before been possible. </p>
<p>While the Parkes telescope is good at finding these radio bursts, telescopes at other wavelengths will ultimately be the next important step in pinning down their origin and natures.</p>
<p>If they give off light at other wavelengths, like X-rays or visible light, picking up important new clues will require a fast response from other telescopes when a radio detection is made. </p>
<p>In the case of FRB 140514, the first multi-wavelength observation didn’t occur until eight hours after the radio burst, preventing us from saying anything definitive about the source.</p>
<h2>Rapid response</h2>
<p>Part of the problem in observing these Fast Radio Bursts is that they only last for a few milliseconds, and the universe is a very big place to look for them. </p>
<p>So finding where they come from means we need to think about more real-time observations and developing a speedier and more collaborative approach to observing any new bursts. The next big breakthrough in the puzzle will come from a faster response to observing and a multi-wavelength effort.</p>
<p>Doing this requires many people. No single individual can watch for bursts 24 hours a day, and no single person can operate dozens of telescopes simultaneously to get the necessary data. Collaborative teams are becoming more important than ever.</p>
<p>The most comprehensive effort currently underway is the Survey for Pulsars and Extragalactic Radio Bursts (<a href="https://sites.google.com/site/publicsuperb/">SUPERB</a>) at Swinburne University.</p>
<p>The aims of the survey, besides finding new Fast Radio Bursts, are to foster international collaboration and develop a robust and fast method for alerting other telescopes with the next real-time discovery.</p>
<p>Ultimately, all we can do is wait for the next burst. Finding a needle in a haystack requires being in the right place at just the right time.</p>
<p>But with more eyes prepared to look and a speedier response we might have a better chance of finding where Fast Radio Bursts really come from.</p><img src="https://counter.theconversation.com/content/36551/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Emily Petroff works for Swinburne University of Technology and is completing a joint PhD with CSIRO Astronomy and Space Science. She is a member of the ARC Centre of Excellence for All-Sky Astrophysics "CAASTRO".</span></em></p>
Astronomers are trying to improve their hunt for rapid bursts of radio emission in the universe called Fast Radio Bursts (FRBs) so they can better observe these mysterious events, which are thought to…
Emily Petroff, PhD candidate in Astro Physics, Swinburne University of Technology
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/15700
2013-07-04T06:14:01Z
2013-07-04T06:14:01Z
Fast Radio Bursts: new intergalactic messengers
<figure><img src="https://images.theconversation.com/files/26737/original/927dhq8n-1372805756.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C2048%2C1152&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Artist's composite of the CSIRO's 64m Parkes Radio Telescope showing an extragalactic radio burst appearing briefly, far from the Milky Way's disk.</span> <span class="attribution"><span class="source">CSIRO/Harvard/Swinburne Astronomy Productions</span></span></figcaption></figure><p>How many electrons are there in the universe? That may seem nigh on impossible to calculate – let alone comprehend – but the discovery of a new population of astrophysical events called Fast Radio Bursts (FRBs), <a href="http://www.sciencemag.org/content/341/6141/53">published in Science today</a> by my colleagues and I, could help provide a solution to this fundamental cosmological question.</p>
<p>The FRBs, discovered with the CSIRO’s Parkes radio telescope in New South Wales, confirm the validity of the amazing “<a href="http://astronomy.swin.edu.au/cosmos/E/Extragalactic+Radio+Bursts">Lorimer burst</a>”, a mysterious event that occurred in 2001 and has until now been quite controversial.</p>
<p>The techniques for finding FRBs closely mirror those used to discover <a href="http://astronomy.swin.edu.au/cosmos/p/pulsar">pulsars</a>, sources of radio emission emitted in lighthouse-like beams first discovered in 1967 by the Northern-Irish astrophysicist <a href="http://en.wikipedia.org/wiki/Jocelyn_Bell_Burnell">Jocelyn Bell</a>.</p>
<p>Though we don’t yet know for sure, it’s worth pointing out that FRBs are probably caused by some catastrophic event in the distant universe. They almost certainly occur in galaxies and probably involve relativistic objects such as <a href="https://theconversation.com/explainer-black-holes-7431">black holes</a> or <a href="http://astronomy.swin.edu.au/cosmos/N/Neutron+Star">neutron stars</a>. </p>
<p>Some candidates are millisecond-duration explosions on the surface of ultra-magnetic neutron stars known as <a href="http://astronomy.swin.edu.au/cosmos/M/Magnetar">magnetars</a>, coalescing neutron stars or <a href="http://astronomy.swin.edu.au/cosmos/S/Supernova">supernova explosions</a>.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/V5p6K6QTJsc?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Finding – and measuring – Fast Radio Bursts.</span></figcaption>
</figure>
<h2>FRB cousins: the gamma-ray bursts</h2>
<p>One of the greatest discoveries of the modern astrophysical era were the <a href="https://theconversation.com/flash-aah-aah-could-a-gamma-ray-burst-eradicate-all-life-on-earth-5291">gamma ray bursts</a>, or GRBs. GRBs are associated with exploding stars and have allowed astronomers to see back until the universe was only a small fraction of its current age. They are short (few second) bursts of gamma-rays that occur infrequently and appear to be randomly distributed on the sky.</p>
<p>The <a href="http://astronomy.swin.edu.au/cosmos/G/Gamma+Ray+Burst+History">first GRBs</a> were found by satellites designed to detect nuclear tests during the Cold War, and to the shock of the engineers involved, seemed to indicate that nuclear tests were being conducted in space!</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/26837/original/984jdy4c-1372894613.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/26837/original/984jdy4c-1372894613.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/26837/original/984jdy4c-1372894613.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=447&fit=crop&dpr=1 600w, https://images.theconversation.com/files/26837/original/984jdy4c-1372894613.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=447&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/26837/original/984jdy4c-1372894613.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=447&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/26837/original/984jdy4c-1372894613.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=562&fit=crop&dpr=1 754w, https://images.theconversation.com/files/26837/original/984jdy4c-1372894613.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=562&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/26837/original/984jdy4c-1372894613.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=562&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">An artist’s impression of a supernova explosion.</span>
<span class="attribution"><span class="source">NASA</span></span>
</figcaption>
</figure>
<p>It took more than 20 years for astronomers to ascertain what the GRBs were, but the mystery was eventually (at least partially) solved when a nearby GRB was associated with a supernova explosion. This led to their correct interpretation and their extreme luminosity has enabled astronomers to learn not only about what the GRBs are, but also about the evolution of the universe.</p>
<h2>Getting to know you</h2>
<p>The FRBs are not (yet) associated with GRBs, but have some similarities. </p>
<p>They are short duration (a few milliseconds) bursts of radio emission that arrive first at high frequencies and then progressively sweep to lower frequencies before disappearing completely and not recurring. The sweep from high radio frequencies to low is called “<a href="http://astronomy.swin.edu.au/cosmos/P/Pulsar+Dispersion+Measure">pulse dispersion</a>”, and has a characteristic form.</p>
<p>On their approximately 10-billion-year intergalactic voyage, every time the radio waves pass an electron they are delayed in a frequency-dependent manner that ultimately amounts to about a one second difference across our observing frequency range. This delay, shown in the figures below, allows us to “count” the number of electrons between us and the burst. </p>
<p>The beautiful sweep and pulse shape of the radiation obeys the theoretically-predicted relation for a burst of radio waves that has propagated across the universe.</p>
<p>Since we think most of the atoms in the universe have lost their electrons, counting them gives us a fundamental insight into the amount of normal or “<a href="http://en.wikipedia.org/wiki/Baryon#Baryonic_matter">baryonic</a>” matter in it. Like the GRBs before them, at present we have no solitary idea of what the FRBs are, and like the GRBs they appear to come from great distances, such as halfway across the observable universe.</p>
<p>A population of FRBs at different stages of the universe’s age would be an invaluable resource, allowing us to map the evolution of the mass distribution. They’re potentially a cosmological gold mine!</p>
<p>But the history of the FRBs has not been without controversy. The first example of an FRB was the famous “Lorimer burst”, mentioned at the outset of this article and <a href="http://www.sciencemag.org/content/318/5851/777.abstract">reported in Science in 2007</a> by astrophysicist Dunc Lorimer and colleagues.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/26596/original/g4pn6t6c-1372655545.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/26596/original/g4pn6t6c-1372655545.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/26596/original/g4pn6t6c-1372655545.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=462&fit=crop&dpr=1 600w, https://images.theconversation.com/files/26596/original/g4pn6t6c-1372655545.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=462&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/26596/original/g4pn6t6c-1372655545.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=462&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/26596/original/g4pn6t6c-1372655545.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=581&fit=crop&dpr=1 754w, https://images.theconversation.com/files/26596/original/g4pn6t6c-1372655545.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=581&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/26596/original/g4pn6t6c-1372655545.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=581&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The ‘waterfall plot’ of the famous ‘Lorimer burst’ showing the characteristic dispersion sweep expected from extragalactic pulses of radio radiation that have travelled cosmological distances. The inset shows the pulse after adding all of the frequency channels and correcting for the sweep.</span>
</figcaption>
</figure>
<p>Unlike most controversial results, the Lorimer burst’s problem was not that it was too weak, but rather that it was too bright! Fainter, more distant analogues should be seen, and none were, despite large international efforts.</p>
<p>Interest in the subject waned - until last year.</p>
<h2>The High Time Resolution Universe Surveys</h2>
<p>Since most pulsars live in our galaxy, pulsar astronomers invariably hunt for them in the plane of the Milky Way; once this area is exhausted they reluctantly move to high galactic latitudes.</p>
<p>The surveys our international team have been conducting at the Parkes 64-metre telescope were no exception.</p>
<p>In mid 2012, University of Manchester PhD student Dan Thornton started looking intensively through the results of the relatively boring “off plane” regions for pulsars, rotating radio transients (short radio pulses), and just maybe, Lorimer bursts.</p>
<p>Dan was somewhat daunted by the presence of radio interference, and his supervisor Ben Stappers suggested he just “set a high threshold” and see if there was anything interesting in his data.</p>
<p>Shortly afterwards he discovered the first burst - FRB 110220 shown below - an amazingly bright pulse and with a dispersion delay some three times that of the Lorimer burst!</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/26601/original/dzj9hg74-1372657942.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/26601/original/dzj9hg74-1372657942.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/26601/original/dzj9hg74-1372657942.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=466&fit=crop&dpr=1 600w, https://images.theconversation.com/files/26601/original/dzj9hg74-1372657942.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=466&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/26601/original/dzj9hg74-1372657942.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=466&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/26601/original/dzj9hg74-1372657942.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=585&fit=crop&dpr=1 754w, https://images.theconversation.com/files/26601/original/dzj9hg74-1372657942.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=585&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/26601/original/dzj9hg74-1372657942.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=585&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Waterfall plot of the fast radio burst FRB 110220 discovered by Dan Thornton (University of Manchester). The image shows the power as a function of time (x axis) for more than 800 radio frequency channels (y axis) and shows the characteristic sweep one expects for sources of galactic and extragalactic origin. In the inset the pulse is shown after summing all the channels and correcting for the dispersion ‘sweep’. The fast rise and exponential decay is characteristic of a pulse scattered by free electrons en route to Earth and both the sweep and scatter tail are compelling evidence of the pulse’s extragalactic origins.</span>
<span class="attribution"><span class="source">Matthew Bailes</span></span>
</figcaption>
</figure>
<p>Director of Germany’s <a href="http://www.mpifr-bonn.mpg.de/2169/en">Max Planck Institute for Radio Astronomy</a> <a href="http://www3.mpifr-bonn.mpg.de/staff/mkramer/About_Me.html">Michael Kramer</a> demonstrated with our new digital equipment the pulse’s dispersion (time delay) sweep could be shown to be perfectly consistent with the theoretically-expected relation, but we still had the problem that we should be seeing other, still weaker, bursts. </p>
<p>Dan soon uncovered two fainter bursts, and then a third, and our confidence in them grew.</p>
<p>The four bursts published in today’s Science paper are certainly consistent with them being part of the same population as the Lorimer burst. The telescope’s observed field of view and event rate suggest that every day, a few thousand similar radio bursts strike Earth; however, we have the instrumentation to detect only one every week or two of observing time, and only when far from the galactic plane.</p>
<p>If we can get more accurate positions, the FRBs will be arguably one of the most important cosmological probes we possess. The combination of a host galaxy <a href="https://theconversation.com/explainer-the-doppler-effect-7475">redshift</a> and the dispersion time provides the mass of normal matter in the universe in a completely new way. </p>
<h2>Origins</h2>
<p>From here, astronomers will pursue the joint aims of determining the origin of the bursts and using them to gain new insights into the universe.</p>
<p>Our team now have a real-time burst detector operating at the <a href="http://astronomy.swin.edu.au/cosmos/P/Parkes+64+metre+radio+telescope">Parkes telescope</a> and are hoping to refurbish the University of Sydney’s old Molonglo radio telescope near Canberra to be a dedicated FRB finder. Looking further afield, the <a href="http://www.skatelescope.org/">Square Kilometre Array</a> and its pathfinders should detect these bursts at rapid rates and allow us to determine their host galaxies.</p>
<p>Last night we found a new event, and the hunt for the origin and physical understanding of these new intergalactic messengers is sure to continue at a furious pace.</p>
<p><br>
<strong>Acknowledgements:</strong></p>
<p><em>I am indebted to the entire HITRUN team [D. Thornton, B.Stappers, B. Barsdell, S. Bates, N. D. R. Bhat, M. Burgay, S. Burke-Spolaor, D. Champion, P. Coster, N. D'Amico, A. Jameson, S. Johnston, M. Keith, M. Kramer, L. Levin, S. Milia, C. Ng, A. Possenti, W. van Straten] and their host institutions, the Universities of Manchester, Swinburne, Curtin, and WVU, INAF, MPI for Radio Astronomy, JPL/Caltech and CSIRO’s CASS division. Special thanks to Dan Thornton for his Jocelyn Bell-like diligence and patience and also to Dunc Lorimer for involving me in the original Lorimer burst discovery and follow-ups. This research is supported in Australia by the ARC and CSIRO’s Astronomy and Space Science division. Matthew Bailes is the Dynamic Universe theme leader of the ARC Centre of Excellence for All-sky Astrophysics “CAASTRO”.</em></p><img src="https://counter.theconversation.com/content/15700/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Matthew Bailes receives funding from the Australian Research Council and Swinburne University of Technology to conduct the research in this piece. He works for Swinburne University of Technology and is the leader of the Dynamic Universe theme of the ARC Centre of Excellence for all-sky astrophysics "CAASTRO".
</span></em></p>
How many electrons are there in the universe? That may seem nigh on impossible to calculate – let alone comprehend – but the discovery of a new population of astrophysical events called Fast Radio Bursts…
Matthew Bailes, Pro-Vice Chancellor (Research) , Swinburne University of Technology
Licensed as Creative Commons – attribution, no derivatives.