tag:theconversation.com,2011:/es/topics/quasar-1817/articlesQuasar – The Conversation2023-09-11T12:34:24Ztag:theconversation.com,2011:article/2113262023-09-11T12:34:24Z2023-09-11T12:34:24ZPowerful black holes might grow up in bustling galactic neighborhoods<figure><img src="https://images.theconversation.com/files/545840/original/file-20230831-17-di646s.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C1280%2C1280&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A quasar is a galactic object with a supermassive black hole in the center. </span> <span class="attribution"><a class="source" href="https://noirlab.edu/public/images/noirlab2015a/">International Gemini Observatory/NOIRLab/NSF/AURA/P. Marenfeld</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-sa/4.0/">CC BY-NC-SA</a></span></figcaption></figure><p>As people, we are all shaped by the neighborhoods we grew up in, whether it was a bustling urban center or the quiet countryside. Objects in distant outer space are no different. </p>
<p>As an <a href="https://www.as.arizona.edu/people/postdoctoral/jaclyn-champagne">astronomer at the University of Arizona</a>, I like to think of myself as a cosmic historian, tracking how supermassive black holes grew up.</p>
<p>Like you, <a href="https://theconversation.com/say-hello-to-sagittarius-a-the-black-hole-at-the-center-of-the-milky-way-galaxy-183008">every supermassive black hole lives in a home</a> – its host galaxy – and a neighborhood – its local group of other galaxies. A supermassive black hole grows by consuming gas already inside its host galaxy, sometimes reaching a billion times heavier than our Sun. </p>
<p>Theoretical physics predicts that black holes should take billions of years to <a href="https://theconversation.com/new-powerful-telescopes-allow-direct-imaging-of-nascent-galaxies-12-billion-light-years-away-74910">grow into quasars</a>, which are extra bright and powerful objects powered by black holes. Yet astronomers know that many quasars have formed in <a href="https://www.eurekalert.org/news-releases/709408">only a few hundred million years</a>.</p>
<p>I’m fascinated by this peculiar problem of faster-than-expected black hole growth and am working to solve it by zooming out and examining the space around these black holes. Maybe the most massive quasars are city slickers, forming in hubs of tens or hundreds of other galaxies. Or maybe quasars can grow to huge proportions even in the most desolate regions of the universe.</p>
<h2>Galaxy protoclusters</h2>
<p>The largest object that can form in the universe is a galaxy cluster, containing hundreds of galaxies pulled by gravity to a common center. Before these grouped galaxies collapse into a single object, astronomers call them <a href="https://doi.org/10.1093/mnras/stv1449">protoclusters</a>. In these <a href="https://www.scientificamerican.com/article/ancient-galaxy-clusters-offer-clues-about-the-early-universe/">dense galaxy neighborhoods</a>, astronomers see colliding galaxies, growing black holes and great swarms of gas that will eventually become the next generation of stars. </p>
<p>These protocluster structures grow much faster than we thought, too, so we have a second cosmic problem to solve – how do quasars and protoclusters evolve so quickly? Are they connected? </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/544797/original/file-20230825-19-i9q2fx.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Red clouds with a bright white center." src="https://images.theconversation.com/files/544797/original/file-20230825-19-i9q2fx.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/544797/original/file-20230825-19-i9q2fx.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=339&fit=crop&dpr=1 600w, https://images.theconversation.com/files/544797/original/file-20230825-19-i9q2fx.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=339&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/544797/original/file-20230825-19-i9q2fx.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=339&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/544797/original/file-20230825-19-i9q2fx.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=426&fit=crop&dpr=1 754w, https://images.theconversation.com/files/544797/original/file-20230825-19-i9q2fx.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=426&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/544797/original/file-20230825-19-i9q2fx.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=426&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 simulation of a galaxy protocluster forming. In white, clouds of dark matter collapse and merge, while the red shows the motions of gas falling into the gravitational pull of the dark matter halos.</span>
<span class="attribution"><a class="source" href="https://www.tng-project.org/media/">TNG Collaboration</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-sa/4.0/">CC BY-NC-SA</a></span>
</figcaption>
</figure>
<p>To look at protoclusters, astronomers ideally <a href="https://theconversation.com/looking-back-toward-cosmic-dawn-astronomers-confirm-the-faintest-galaxy-ever-seen-207602">obtain images</a>, which show the galaxy’s shape, size and color, and a spectrum, which shows the galaxy’s distance from Earth through specific wavelengths of light, for each galaxy in the protocluster. </p>
<p>With telescopes like the James Webb Space Telescope, astronomers can see galaxies and black holes <a href="https://theconversation.com/the-most-powerful-space-telescope-ever-built-will-look-back-in-time-to-the-dark-ages-of-the-universe-169603">as they were billions of years ago</a>, since the light emitted from distant objects must travel billions of light-years to reach its detectors. We can then look at protoclusters’ and quasars’ baby pictures to see how they evolved at early times.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/545633/original/file-20230830-17-gwpqna.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A graph with the y axis reading 'brightness' and the x reading 'wavelength.' A squiggly green line has peaks, with an arrow pointing to the reading 'hydrogen' and 'oxygen.'" src="https://images.theconversation.com/files/545633/original/file-20230830-17-gwpqna.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/545633/original/file-20230830-17-gwpqna.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=300&fit=crop&dpr=1 600w, https://images.theconversation.com/files/545633/original/file-20230830-17-gwpqna.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=300&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/545633/original/file-20230830-17-gwpqna.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=300&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/545633/original/file-20230830-17-gwpqna.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=377&fit=crop&dpr=1 754w, https://images.theconversation.com/files/545633/original/file-20230830-17-gwpqna.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=377&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/545633/original/file-20230830-17-gwpqna.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">An example of a galaxy image and spectrum from the ASPIRE program at the University of Arizona. The inset shows the infrared image of a galaxy 800 million years after the Big Bang. The spectrum shows signatures of hydrogen and oxygen emission lines, whose wavelengths translate mathematically to a 3D location in space.</span>
<span class="attribution"><span class="source">J. Champagne/ASPIRE/University of Arizona</span></span>
</figcaption>
</figure>
<p>It is only after looking at spectra that astronomers determine whether the galaxies and quasars are actually close together in three-dimensional space. But getting spectra for every galaxy one at a time can take many more hours than any astronomer has, and images can show galaxies that look <a href="https://doi.org/10.3847/1538-4357/acda8d">closer together than they actually are</a>. </p>
<p>So, for a long time, it was only a prediction that massive quasars might be evolving at the centers of vast galactic cities. </p>
<h2>An unprecedented view of quasar environments</h2>
<p>Now, Webb has completely revolutionized the search for galaxy neighborhoods because of an instrument called a <a href="https://webb.nasa.gov/content/observatory/instruments/nircam.html">wide-field slitless spectrograph</a>. </p>
<p>This instrument takes spectra of every galaxy in its field of view simultaneously so astronomers can map out an entire cosmic city at once. It encodes the critical information about galaxies’ 3D locations by capturing the light emitted from gas at specific wavelengths – and in only a few hours of observing time.</p>
<p>The first Webb projects are hoping to look at quasar environments focused on a period about 800 million years after the Big Bang. This time period is a sweet spot in which astronomers can view these monster quasars and their neighbors using the light emitted by hydrogen and oxygen. The wavelengths of these light features show where the objects emitting them are along our line of sight, allowing astronomers to complete the census of where galaxies live relative to bright quasars.</p>
<p>One such ongoing project is led by <a href="https://aspire-quasar.github.io/">the ASPIRE team</a> at the University of Arizona’s Steward Observatory. In an <a href="https://webbtelescope.org/contents/news-releases/2023/news-2023-124?user=choquet">early paper</a>, they found a protocluster around an extremely bright quasar and confirmed it with 12 galaxies’ spectra. </p>
<p><a href="https://doi.org/10.3847/1538-4357/acc588">Another study</a> detected over a hundred galaxies, looking toward the single most luminous quasar known in the early universe. Twenty-four of those galaxies were close to the quasar or in its neighborhood.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/544641/original/file-20230824-23-4uejft.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Many bright dots representing galaxies, against a black backdrop." src="https://images.theconversation.com/files/544641/original/file-20230824-23-4uejft.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/544641/original/file-20230824-23-4uejft.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=704&fit=crop&dpr=1 600w, https://images.theconversation.com/files/544641/original/file-20230824-23-4uejft.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=704&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/544641/original/file-20230824-23-4uejft.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=704&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/544641/original/file-20230824-23-4uejft.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=885&fit=crop&dpr=1 754w, https://images.theconversation.com/files/544641/original/file-20230824-23-4uejft.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=885&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/544641/original/file-20230824-23-4uejft.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=885&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 neighborhood of galaxies around J0305-3150, a quasar identified approximately 800 million years after the Big Bang.</span>
<span class="attribution"><a class="source" href="https://webbtelescope.org/contents/news-releases/2023/news-2023-124">STScI/NASA</a></span>
</figcaption>
</figure>
<p>In ongoing work, my team is learning more details about mini galaxy cities like these. We want to figure out if individual galaxies show high rates of new star formation, if they contain large masses of old stars or if they are merging with one another. All these metrics would indicate that these galaxies are still actively evolving but had already formed millions of years before we observed them.</p>
<p>Once my team has a list of the properties of the galaxies in an area, we’ll compare these properties with a control sample of random galaxies in the universe, far away from any quasar. If these metrics are different enough from the control, we’ll have good evidence that quasars do grow up in special neighborhoods – ones developing much faster than the more sparse regions of the universe. </p>
<p>While astronomers still need more than a handful of quasars to prove this hypothesis on a larger scale, Webb has already opened a window into a bright future of discovery in glorious, high-resolution detail.</p><img src="https://counter.theconversation.com/content/211326/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jaclyn Champagne receives funding from the National Science Foundation and the Space Telescope Science Institute. The results from ASPIRE are supported by data and funding from JWST program GO-2078. The data were obtained from the Mikulski Archive for Space Telescopes at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-03127 for JWST. </span></em></p>An astronomer and ‘black hole historian’ explains how the parts of the universe black holes grow in might influence how quickly they become bright, supermassive objects.Jaclyn Champagne, JASPER Postdoctoral Researcher, University of ArizonaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1847732022-06-13T12:00:59Z2022-06-13T12:00:59ZGaia mission: five insights astronomers could glean from its latest data<figure><img src="https://images.theconversation.com/files/468179/original/file-20220610-35158-mfvhp4.jpg?ixlib=rb-1.1.0&rect=27%2C32%2C3076%2C2003&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Gaia mapping the stars of the Milky Way.</span> <span class="attribution"><span class="source">ESA/ATG medialab; background: ESO/S. Brunier</span>, <a class="license" href="http://creativecommons.org/licenses/by-nc/4.0/">CC BY-NC</a></span></figcaption></figure><p>The European Space Agency’s (Esa) <a href="https://theconversation.com/gaia-mission-releases-map-of-more-than-a-billion-stars-heres-what-it-can-teach-us-95602">Gaia mission</a> has just released new data. The Gaia satellite was launched in 2013, with the aim of measuring the precise positions of a billion stars. In addition to measuring the stars’ positions, speeds and brightness, the satellite has collected data on a huge range of other objects.</p>
<p>There’s a lot to <a href="https://theconversation.com/how-were-helping-the-gaia-mission-map-a-billion-stars-to-unparalleled-precision-65602">make astronomers excited</a>. Here are five of our favourite insights that the data might provide.</p>
<h2>1. Secrets of our galaxy’s past and future</h2>
<p>Everything in space is moving, and the stars are no exception. The latest release of data contains the largest three-dimensional map of the Milky Way ever produced - showing how the stars in our galaxy are travelling. Previous data included the motions of stars in two dimensions: up-down and left-right (known collectively as stars’ <a href="https://sci.esa.int/web/gaia/-/60224-parallax-and-proper-motion-on-the-sky">proper motions</a>). But the latest data also shows how quickly stars are moving away from us or towards us, something we call the stars’ radial velocities.</p>
<p>By combining the radial velocity with the proper motions, we can find out how quickly stars are moving in three dimensions as they orbit the Milky Way. This means we now have not only the best map of where the galaxy’s stars are now, but we can track their motions forward to see how things will change, and backward to see how things used to be. </p>
<p>This can tell us things about our galaxy’s history, such as which stars may have come from other galaxies and merged with our own in the past. Radial velocity measurements can also help us find hidden objects, such as planets and <a href="https://theconversation.com/exoplanet-discovery-blurs-the-line-between-large-planets-and-small-stars-124150">brown dwarfs</a> (extremely faint stars with low mass), from the tiny wobbles they cause as they orbit a host star.</p>
<h2>2. Details of how stars die</h2>
<p>Gaia is not just measuring the stars in our own galaxy, it also measures those in the neighbouring Andromeda galaxy. The data includes something called Gaps: <a href="https://www.cosmos.esa.int/web/gaia/newsletter/contents">the Gaia Andromeda photometric survey</a>. A photometric survey measures the brightness of stars and how they change over time. With Gaps, Gaia has measured the brightness over time for every star in the direction of the Andromeda galaxy.</p>
<p>That includes 1.2 million stars. Some of those will be foreground stars in the Milky Way that happened to be in the way, but it should include roughly the brightest 1% of stars in the Andromeda galaxy. This will allow us to study the way that the largest, most luminous stars in Andromeda change in brightness, telling us about their evolution and where they are in their life cycles.</p>
<p>This could tell us more about old stars that are reaching the ends of their lives - some of which could go on to produce supernovas (huge explosions) eventually.</p>
<h2>3. The truth about the universe’s strange expansion</h2>
<p><a href="https://earthsky.org/astronomy-essentials/definition-what-is-a-quasar/">Quasars</a>, extremely energetic cores of galaxies at the edge of the observable universe, are the most luminous objects in the universe and the most distant objects we can see. And the new data includes measurements of 1.1 million of them. Quasars contain supermassive black holes that are caught in a violent feeding frenzy. In addition to these confirmed quasars, Gaia has found a further 6.6 million quasar candidates. </p>
<figure class="align-center ">
<img alt="Schematic image of the universe's expansion." src="https://images.theconversation.com/files/292202/original/file-20190912-190012-1sio7rp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/292202/original/file-20190912-190012-1sio7rp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=396&fit=crop&dpr=1 600w, https://images.theconversation.com/files/292202/original/file-20190912-190012-1sio7rp.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=396&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/292202/original/file-20190912-190012-1sio7rp.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=396&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/292202/original/file-20190912-190012-1sio7rp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=498&fit=crop&dpr=1 754w, https://images.theconversation.com/files/292202/original/file-20190912-190012-1sio7rp.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=498&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/292202/original/file-20190912-190012-1sio7rp.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=498&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Universe’s expansion.</span>
<span class="attribution"><span class="source">NASA/WMAP</span></span>
</figcaption>
</figure>
<p>This potentially vastly increases the number of known quasars, and that could be very important because they let us measure the distance to the furthest reaches of the universe. This in turn lets us measure how quickly the universe is expanding. Being able to measure that more accurately is important, because we have two <a href="https://theconversation.com/the-universes-rate-of-expansion-is-in-dispute-and-we-may-need-new-physics-to-solve-it-100154">conflicting measurements of the expansion</a>, and we don’t know which one is right – the problem is called “the Hubble tension”.</p>
<h2>4. How many asteroids have moons</h2>
<p>Not everything Gaia is studying is so far from home. The data contains 158,000 objects in our own Solar System. That includes new measurements of 156,000 known asteroids, telling us exactly what paths they follow as they orbit the Sun. </p>
<p>Not only that, but the Gaia team has shown that they are able to find moons orbiting asteroids, based on how the moons make the asteroids wobble. A few hundred asteroids with moons are already known, but Gaia can find asteroid moons even when the moon is too small to see directly. It can also measure the positions of asteroids so accurately that it sees the slight wobble in the position caused by a moon’s gravity. Esa says the latest data contains at least one such new moon, but there could be a lot more.</p>
<figure class="align-center ">
<img alt="Image of asteroids around the Sun as seen by Gaia." src="https://images.theconversation.com/files/468396/original/file-20220613-43540-h2o15v.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/468396/original/file-20220613-43540-h2o15v.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=604&fit=crop&dpr=1 600w, https://images.theconversation.com/files/468396/original/file-20220613-43540-h2o15v.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=604&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/468396/original/file-20220613-43540-h2o15v.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=604&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/468396/original/file-20220613-43540-h2o15v.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=759&fit=crop&dpr=1 754w, https://images.theconversation.com/files/468396/original/file-20220613-43540-h2o15v.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=759&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/468396/original/file-20220613-43540-h2o15v.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=759&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Asteroids around the Sun as seen by Gaia. Each asteroid is a segment representing its motion over 10 days (with blue representing the inner solar system).</span>
<span class="attribution"><span class="source">ESA/Gaia/DPAC</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>Gathering better data about asteroids can tell us about the chaos of the early Solar System when the larger planets threw smaller planets and asteroids into new orbits around the Sun and led to the solar system of today.</p>
<h2>5. How stars form and operate</h2>
<p>Our Sun is a solitary star, but many stars have companions – <a href="https://www.atnf.csiro.au/outreach/education/senior/astrophysics/binary_intro.html">orbiting each other around a shared centre</a>. The new data contains the first taste of Gaia’s catalogue of such multiple-star systems. This is an initial list, with the full catalogue to come in a later data release, but it already contains 813,000 binary (two-star) systems.</p>
<p>Binary stars can tell us a lot about how stars work and how they are formed. This is especially true for what are called eclipsing binary systems. These are binary systems that happen to be lined up so that the stars pass in front of each other from our point of view. Eclipsing binaries are special because we can take measurements of them to work out all the physical properties of the system, such as the stars’ masses and sizes, and how far away they are. This allows us to learn far more than we could from studying single stars.</p>
<p>This new data will excite astrophysicists around the world, and we can’t wait to get stuck into it to see what we can find. We might have some of these answers in the next few months, while others might take longer.</p><img src="https://counter.theconversation.com/content/184773/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Adam McMaster receives funding from the Science and Technology Facilities Council, DISCnet, and the Open University Space SRA.</span></em></p><p class="fine-print"><em><span>Andrew Norton 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>New data may settle dispute about the universe’s true expansion rate.Adam McMaster, PhD Candidate, Astronomy, The Open UniversityAndrew Norton, Professor of Astrophysics Education, The Open UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1536502021-02-07T19:05:26Z2021-02-07T19:05:26Z5 twinkling galaxies help us uncover the mystery of the Milky Way’s missing matter<figure><img src="https://images.theconversation.com/files/382678/original/file-20210205-14-1cjaiyy.jpg?ixlib=rb-1.1.0&rect=57%2C38%2C6332%2C3554&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption"></span> <span class="attribution"><span class="license">Author provided</span></span></figcaption></figure><p>We’ve all looked up at night and admired the brightly shining stars. Beyond making a gorgeous spectacle, measuring that light helps us learn about matter in our galaxy, the Milky Way.</p>
<p>When astronomers add up all the ordinary matter detectable around us (such as in galaxies, stars and planets), they find only half the amount expected to exist, based on predictions. This normal matter is “<a href="https://www.space.com/20930-dark-matter.html">baryonic</a>”, which means it’s made up of baryon particles such as protons and neutrons.</p>
<p>But about half of this matter in our galaxy is too dark to be detected by even the most powerful telescopes. It takes the form of cold, dark clumps of gas. In this dark gas is the Milky Way’s “missing” baryonic matter. </p>
<p>In a <a href="https://academic.oup.com/mnras/advance-article-abstract/doi/10.1093/mnras/stab139/6105310">paper</a> published in the Monthly Notices of the Royal Astronomical Society, we detail the discovery of five twinkling far-away galaxies that point to the presence of an unusually shaped gas cloud in the Milky Way. We think this cloud may be linked to the missing matter.</p>
<h2>Finding what we can’t see</h2>
<p>Stars twinkle because of turbulence in our atmosphere. When their light reaches Earth, it gets bent as it bounces through different layers of the atmosphere.</p>
<p>Rarely, galaxies can twinkle too, due to the turbulence of gas in the Milky Way. We see this twinkling because of the luminous cores of distant galaxies named “quasars”.</p>
<p>Astronomers can use quasars a bit like backlights, to reveal the presence of clumps of gas around us that would otherwise be impossible to see. The challenge, however, is that it is very rare to catch quasars twinkling.</p>
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<strong>
Read more:
<a href="https://theconversation.com/curious-kids-why-do-stars-twinkle-81188">Curious Kids: Why do stars twinkle?</a>
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<p>This is where the <a href="https://theconversation.com/the-australian-square-kilometre-array-pathfinder-finally-hits-the-big-data-highway-71217">Australian Square Kilometre Array Pathfinder</a> (ASKAP) comes in. This highly sensitive telescope can view an area about the size of the Southern Cross and detect tens of thousands of distant galaxies, including quasars, in a single observation. </p>
<p>Using ASKAP, we looked at the same patch of sky seven times. Of the 30,000 galaxies we could see, six were twinkling strongly. Surprisingly, five of these were arranged in a long, thin straight line.</p>
<p>Analysis showed we’d captured an invisible clump of gas between us and the galaxies. As light from the galaxies passed through the gas cloud, they appeared to twinkle. </p>
<iframe src="https://giphy.com/embed/IbzBKUczcgumPpSq1Z" width="100%" height="360" frameborder="0" class="" allow="" fullscreen=""></iframe>
<p> At the centre is one of the strongly twinkling galaxies. The colours represent brightness, as it fluctuates between shining brightly (red) and more faintly (blue). </p>
<h2>A clump of gas ten light years away</h2>
<p>The cloud of gas we detected was inside the Milky Way, about ten light years away from Earth. For reference, one light year is 9.7 trillion kilometres. </p>
<p>That means light from those twinkling galaxies travelled billions of light years towards Earth, only to be disrupted by the cloud during the last ten years of its journey. </p>
<p>By observing the sky positions of not just the five twinkling galaxies, but also tens of thousands of non-twinkling ones, we were able to draw a boundary around the gas cloud.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/380428/original/file-20210125-19-12u4kcg.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/380428/original/file-20210125-19-12u4kcg.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=476&fit=crop&dpr=1 600w, https://images.theconversation.com/files/380428/original/file-20210125-19-12u4kcg.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=476&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/380428/original/file-20210125-19-12u4kcg.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=476&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/380428/original/file-20210125-19-12u4kcg.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=599&fit=crop&dpr=1 754w, https://images.theconversation.com/files/380428/original/file-20210125-19-12u4kcg.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=599&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/380428/original/file-20210125-19-12u4kcg.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=599&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">We were intrigued by the sky positions of the twinkling galaxies in our ASKAP observations. Each black dot above represents a brightly-shining, distant object.</span>
<span class="attribution"><span class="source">Yuanming Wang</span></span>
</figcaption>
</figure>
<p>We found it was very straight, the same length as four Moons side-by-side, and only two “<a href="https://earthsky.org/astronomy-essentials/sky-measurements-degrees-arc-minutes-arc-seconds">arcminutes</a>” in width. This is so thin it’s the equivalent of looking at a strand of hair held at arm’s length. </p>
<p>This is the first time astronomers have been able to calculate the geometry and physical properties of a gas cloud in this way. But where did it come from? And what gave it such an unusual shape?</p>
<h2>It’s freezing out there</h2>
<p>Astronomers have predicted that when a star passes too close to a black hole, the extreme forces from the black hole will pull it apart, resulting in a long, thin gas stream. </p>
<p>But there are no massive black holes near that cloud of gas — the <a href="https://www.bbc.com/news/science-environment-52560812">closest one we know about</a> is more than 1,000 light years from Earth.</p>
<p>So we propose another theory: that a hydrogen “snow cloud” was disrupted and stretched out by gravitational forces from a nearby star, turning into a long thin gas cloud. </p>
<p>Snow clouds have only been studied as theoretical possibilities and are almost impossible to detect. But they would be so cold that droplets of hydrogen gas within them could freeze solid. </p>
<p>Some astronomers believe snow clouds make up part of the missing matter in the Milky Way.</p>
<p>It’s incredibly exciting for us to have measured an invisible clump of gas in such detail, using the ASKAP telescope. In the future we plan to repeat our experiment on a much larger scale and hopefully create a “cloud map” of the Milky Way. </p>
<p>We’ll then be able to work out how many other gas clouds are out there, how they’re distributed and what role they might have played in the evolution of the Milky Way.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/half-the-matter-in-the-universe-was-missing-we-found-it-hiding-in-the-cosmos-138569">Half the matter in the universe was missing – we found it hiding in the cosmos</a>
</strong>
</em>
</p>
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<img src="https://counter.theconversation.com/content/153650/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Yuanming Wang receives support from China Scholarship Council, and as a Graduate Student with the University of Sydney and CSIRO Astronomy and Space Science.</span></em></p><p class="fine-print"><em><span>Tara Murphy works for the University of Sydney. She receives funding from the Australian Research Council and is an Associate Investigator in the OzGrav Centre of Excellence for Gravitational Wave Discovery.</span></em></p>Thanks to the discovery of five twinkling galaxies in a rare alignment, astronomers have been able to calculate — for the first time — the properties and geometry of an invisible gas cloud in space.Yuanming Wang, PhD student, University of SydneyTara Murphy, Professor, University of SydneyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/749102017-03-23T18:01:35Z2017-03-23T18:01:35ZNew powerful telescopes allow direct imaging of nascent galaxies 12 billion light years away<figure><img src="https://images.theconversation.com/files/162115/original/image-20170323-25783-1fgo3vq.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Artist's impression of a quasar shining through a galaxy's 'super halo' of hydrogen gas.</span> <span class="attribution"><span class="source">A. Angelich (NRAO/AUI/NSF)</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span></figcaption></figure><p>How does a galaxy like our own Milky Way form? Until now there’s been a lot of inferring involved in answering that question.</p>
<p>The basic story is that gas collects toward the center of roughly spherical “halos” of matter. The gas then cools, condenses, fragments and eventually collapses to form stars. Generations of stars build up the galaxy and with it the production of heavy elements – such as carbon, oxygen and so on – that populate our periodic table and comprise our familiar physical world.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/162105/original/image-20170322-25776-tjaa1.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/162105/original/image-20170322-25776-tjaa1.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/162105/original/image-20170322-25776-tjaa1.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/162105/original/image-20170322-25776-tjaa1.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/162105/original/image-20170322-25776-tjaa1.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/162105/original/image-20170322-25776-tjaa1.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/162105/original/image-20170322-25776-tjaa1.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/162105/original/image-20170322-25776-tjaa1.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">Numerical visualizations of the stars in galaxies forming in the early universe.</span>
<span class="attribution"><span class="source">The Eagle Project, Durham University</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>Astrophysicists like me have pieced together this picture thanks largely to theoretical research. <a href="http://icc.dur.ac.uk/Eagle/about.php">We run numerical simulations</a> on the world’s largest supercomputers to capture the processes that govern galaxy formation – <a href="http://physics.stackexchange.com/questions/167496/what-happens-during-gravitational-collapse-to-cause-the-formation-of-a-star">gravitational collapse</a>, heating, <a href="https://en.wikipedia.org/wiki/Radiative_cooling">radiative cooling</a> – at high fidelity.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/162107/original/image-20170322-25783-y93wje.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/162107/original/image-20170322-25783-y93wje.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/162107/original/image-20170322-25783-y93wje.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/162107/original/image-20170322-25783-y93wje.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/162107/original/image-20170322-25783-y93wje.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/162107/original/image-20170322-25783-y93wje.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/162107/original/image-20170322-25783-y93wje.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/162107/original/image-20170322-25783-y93wje.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">Numerical simulation of gas corresponding to the same region as the previous figure. Young galaxies are dominated by gas and not stars.</span>
<span class="attribution"><span class="source">The Eagle Project, Durham University</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>To study many of these processes, we were largely restricted to this kind of theoretical inquiry because we didn’t have the technical capacity to observe them. But things have changed as we’ve witnessed the rise of what we consider the “Great Observatories”: NASA’s <a href="https://www.nasa.gov/mission_pages/hubble/story/index.html">Hubble Space Telescope</a>, the twin 10m <a href="http://www.keckobservatory.org/">Keck Telescopes</a> on Manua Kea, Hawaii, and, most recently, the <a href="https://public.nrao.edu/telescopes/alma">Atacama Large Millimeter/submillimeter Array</a> (ALMA) in northern Chile. With these facilities, astronomers have sought to test and refine the tenets of galaxy formation theory, especially the processes governing galaxy assembly and star formation.</p>
<p><a href="http://science.sciencemag.org/cgi/doi/10.1126/science.aal1737">The new data</a> our group is publishing based on observations from ALMA are truly transformative relative to previous observations. They allow us to directly image the gas in nascent galaxies – something that was impossible before – and thereby test our fundamental predictions of galaxy formation.</p>
<h2>The physical challenge</h2>
<p>When we try to directly observe distant galaxies, the principal challenge is the very faint signal that reaches Earth from such great distances. The light from the two galaxies studied in our publication, for example, has traveled 12 billion light years to get here. This also means the light was emitted 12 billion years ago, when the universe was only 1.5 billion years old and galaxies were mere adolescents. And I’m especially interested in studying the gas that fuels star formation, which is particularly difficult to detect.</p>
<p>To address this challenge, starting in 1986 our group – led by <a href="http://dx.doi.org/10.1063/PT.3.2558">the late Arthur M. Wolfe</a> – relied on an indirect way to study distant galaxies. Rather than focusing on the galaxies themselves, we recorded the light from quasars that are even farther away from us. This allows us to probe gas in foreground galaxies.</p>
<p><a href="http://www.space.com/17262-quasar-definition.html">Quasars</a> are exceedingly bright objects that are powered by supermassive black holes. As a quasar’s light travels through the galactic gas we’re actually interested in, the atoms in the gas scatter a small portion of the light <a href="https://theconversation.com/explainer-seeing-the-universe-through-spectroscopic-eyes-37759">at well-defined wavelengths</a>. It’s these so-called <a href="http://astronomy.swin.edu.au/cosmos/A/Absorption+Line">absorption signatures</a> in the quasar’s spectrum that we focus on. The gas is imprinting its signature on the light we can collect with our telescopes. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/162259/original/image-20170323-4948-9dhkv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/162259/original/image-20170323-4948-9dhkv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/162259/original/image-20170323-4948-9dhkv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/162259/original/image-20170323-4948-9dhkv.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/162259/original/image-20170323-4948-9dhkv.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/162259/original/image-20170323-4948-9dhkv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/162259/original/image-20170323-4948-9dhkv.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/162259/original/image-20170323-4948-9dhkv.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">Light from a distant quasar passes through intervening gas clouds in galaxies and in intergalactic space. These clouds of primeval hydrogen subtract specific colors from the beam. The resulting ‘absorption spectrum’ can help determine the distances and chemical composition of the invisible clouds.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Cumulative-absorption-spectrum-hubble-telescope.jpg">NASA/STScI</a></span>
</figcaption>
</figure>
<p>We pass the light our telescope gathers through a <a href="http://coolcosmos.ipac.caltech.edu/ask/291-What-is-a-spectrometer-">spectrometer</a>, an instrument that allows us to study the brightness as a function of wavelength. Then we can infer that there is in fact gas present between us and the quasar and we can quantitatively measure various properties of the gas. </p>
<p>Arthur used spectrometers at the primary observing suite of the <a href="https://www.ucolick.org/">University of California Observatories</a>, first instruments on the <a href="https://www.ucolick.org/public/telescopes/shane.html">Shane 3m</a> telescope of the Lick Observatory and then, upon being commissioned, led research on the powerful Keck telescopes. These data <a href="http://doi.org/10.1146/annurev.astro.42.053102.133950">provide estimates</a> on the gas surface density, heavy element enrichment, molecular content and dynamical motions of the galaxy. </p>
<p>This observational experiment, however, is limited. It offers little information on the galaxy’s mass, size or star formation – all things that are fundamental to a galaxy’s makeup. It is critical that we measure these properties to understand the formation history of galaxies like our Milky Way. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/162112/original/image-20170323-25751-ar820.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/162112/original/image-20170323-25751-ar820.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/162112/original/image-20170323-25751-ar820.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=403&fit=crop&dpr=1 600w, https://images.theconversation.com/files/162112/original/image-20170323-25751-ar820.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=403&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/162112/original/image-20170323-25751-ar820.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=403&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/162112/original/image-20170323-25751-ar820.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=507&fit=crop&dpr=1 754w, https://images.theconversation.com/files/162112/original/image-20170323-25751-ar820.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=507&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/162112/original/image-20170323-25751-ar820.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=507&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 Atacama Large Millimeter/submillimeter Array is made up of 66 antennas, all pointed at the sky collecting data 24 hours a day.</span>
<span class="attribution"><a class="source" href="http://www.almaobservatory.org/en/visuals/images/antennas-and-transporters">ESO/B. Tafreshi (twanight.org)</a></span>
</figcaption>
</figure>
<h2>Next-generation observations</h2>
<p>In 2003, we reported that the then-future <a href="http://iopscience.iop.org/article/10.1086/376520/meta">ALMA telescope would be a true game-changer</a> by enabling us to directly image the gas within nascent galaxies. We would have to wait over a decade to begin while the telescope was built – so we had plenty of time to carefully identify the optimal targets and refine our observing strategies.</p>
<p>All the waiting and planning have now paid off. Arthur’s last Ph.D. student, Marcel Neeleman, <a href="http://science.sciencemag.org/cgi/doi/10.1126/science.aal1737">just published our first results with ALMA</a> and the data are spectacular. Here, in contrast to our previous work, we measure light from the gas in the galaxy itself, which reveals the size and shape of the star-forming regions. And what we saw was not what we expected.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/162114/original/image-20170323-25751-2uzio2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/162114/original/image-20170323-25751-2uzio2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/162114/original/image-20170323-25751-2uzio2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/162114/original/image-20170323-25751-2uzio2.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/162114/original/image-20170323-25751-2uzio2.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/162114/original/image-20170323-25751-2uzio2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/162114/original/image-20170323-25751-2uzio2.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/162114/original/image-20170323-25751-2uzio2.jpg?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">Map of one galaxy’s emission from ionized carbon, taken with the ALMA telescope. These data reveal and resolve the star-forming regions within young, forming galaxies.</span>
<span class="attribution"><span class="source">Neeleman et al doi: 10.1126/science.aal1737</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>ALMA collects light at wavelengths not visible to the human eye. We focused on two sources in our target galaxies: ionized carbon and warm dust, both of which surround the birthplace of new stars. We were able to create maps based on the light emitted by ionized carbon within a galaxy that we first detected in absorption, via our old technique. </p>
<p>Remarkably, the dense, star-forming gas of the galaxy is greatly offset from the hydrogen gas originally revealed by the quasar spectrum (by approximately 100,000 light years or 30 kiloparsecs). This distance shows that young galaxies are surrounded by a massive reservoir of un-ionized, neutral gas. We further suggest that the gas detected in absorption is likely to accrete back onto the galaxy and fuel future generations of stars.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/162207/original/image-20170323-4961-16i99j5.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/162207/original/image-20170323-4961-16i99j5.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/162207/original/image-20170323-4961-16i99j5.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=286&fit=crop&dpr=1 600w, https://images.theconversation.com/files/162207/original/image-20170323-4961-16i99j5.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=286&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/162207/original/image-20170323-4961-16i99j5.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=286&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/162207/original/image-20170323-4961-16i99j5.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=359&fit=crop&dpr=1 754w, https://images.theconversation.com/files/162207/original/image-20170323-4961-16i99j5.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=359&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/162207/original/image-20170323-4961-16i99j5.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=359&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Spectral image of one galaxy’s light. Horizontal axis describes the size of the galaxy and the vertical axis describes the motion of the gas. Analysis of the image reveals the gas is rotating in a disk, like our own spiral galaxy.</span>
<span class="attribution"><span class="source">Neeleman et al doi: 10.1126/science.aal1737</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>The ALMA data also uniquely resolve the internal motions of the galaxy’s gas. Our analysis of the dynamics indicates the gas is configured in a large disk – similar to our Milky Way – and rotating with a speed of approximately 120 km/s. This speed is characteristic of what theory predicts for the progenitors of this sort of galaxy. </p>
<p>Lastly, we detected emission from “warm” dust in the galaxy. (Of course, warm is relative – in this case only about 30 degrees Celsius above absolute zero.) We believe the dust is heated by young massive stars; we estimate that the galaxy is forming stars at a rate of over 100 suns per year, a prodigious and precocious rate. </p>
<p>These data demonstrate the power and potential of ALMA to discover and dissect the progenitors of galaxies like our own. They will be invaluable to refine our understanding – in space and time – of the build-up of galaxies.</p>
<figure>
<iframe src="https://player.vimeo.com/video/209248385" width="500" height="281" frameborder="0" webkitallowfullscreen="" mozallowfullscreen="" allowfullscreen=""></iframe>
<figcaption><span class="caption">Milky Way-like galaxies in the early universe.</span></figcaption>
</figure>
<p>While many of us in the community held some reservations about ALMA (given its great cost), it is now clear to me the payoff will be extraordinary. ALMA research has already paid off in the discovery of <a href="http://www.almaobservatory.org/en/press-room/press-releases/937-almas-best-image-yet-of-a-protoplanetary-disk">protoplanetary disks</a> from which planets form and unlocked hidden secrets of the process of <a href="http://www.almaobservatory.org/en/about-alma/science-with-alma/star-and-planet-formation">star formation</a>. And ALMA will continue to greatly advance our understanding of how galaxies like the Milky Way form.</p>
<hr>
<p><em>Editor’s note: On May 20, 2020, the author and colleagues published <a href="https://doi.org/10.1038/s41586-020-2276-y">new research in the journal Nature</a> that used sharper images from the ALMA telescope to reveal that one galaxy is a rapidly rotating disk galaxy. It’s remarkably similar to our own Milky Way despite its very young age. They named this galaxy the Wolfe Disk in honor of the scientific contributions of Arthur Wolfe and his prediction that such galaxies would exist.</em></p><img src="https://counter.theconversation.com/content/74910/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>Astronomers are surprised by what they’re finding out about galaxies that formed in the early days of our universe, now that sensitive telescopes allow direct observation, not the inference of old.J. Xavier Prochaska, Professor of Astronomy & Astrophysics, University of California, Santa CruzLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/534422016-01-21T19:19:07Z2016-01-21T19:19:07ZMysterious blobs in our Milky Way could be part of the missing matter<figure><img src="https://images.theconversation.com/files/108689/original/image-20160120-26120-pahuxm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">CSIRO's Compact Array telescope under the Milky Way.</span> <span class="attribution"><span class="source">Alex Cherney</span>, <span class="license">Author provided</span></span></figcaption></figure><p>A plethora of missing matter problems besieges astronomy. Most famously, <a href="https://theconversation.com/au/topics/dark-matter">dark matter</a>, which was postulated to solve the problem of why galaxies spin so fast (among other things), is thought to comprise some 23% of the mass-energy of the universe.</p>
<p>It is yet to be detected by direct means and remains one of the most significant puzzles in modern astronomy and physics.</p>
<p>Even putting aside dark matter, astronomers are still unable to account for roughly 5% of the universe thought to be made of normal matter, known as baryons. This question, known as the <a href="http://www.scientificamerican.com/article/the-milky-way-s-missing-mass-partially-found/">missing baryon problem</a> is of particular interest here.</p>
<p>Where is all the stuff?</p>
<p>Well, we may have found at least some of those baryons, with the details on how <a href="http://science.sciencemag.org/content/351/6271/354">published in Science</a> today. But first, a bit of history.</p>
<h2>A wine glass in the sky</h2>
<p>In 1987, astronomers found the radio waves from a <a href="https://astronomy.swin.edu.au/cms/astro/cosmos/*/Quasar">quasar</a> that was normally reasonably constant, varying wildly for a period of a few months. They immediately concluded that the cause of the variation was not the quasar itself, but <a href="http://sciencelearn.org.nz/Contexts/Light-and-Sight/Science-Ideas-and-Concepts/Refraction-of-light">refraction</a> through a blob of <a href="http://pluto.space.swri.edu/image/glossary/plasma.html">plasma</a> in our own Milky Way.</p>
<p>You can imagine the blob as a wine glass, sitting on a table during a sunny day. The light from the sun shines through the glass, and makes a pattern on the table.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/108686/original/image-20160120-26079-1oltp03.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/108686/original/image-20160120-26079-1oltp03.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/108686/original/image-20160120-26079-1oltp03.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=374&fit=crop&dpr=1 600w, https://images.theconversation.com/files/108686/original/image-20160120-26079-1oltp03.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=374&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/108686/original/image-20160120-26079-1oltp03.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=374&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/108686/original/image-20160120-26079-1oltp03.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=470&fit=crop&dpr=1 754w, https://images.theconversation.com/files/108686/original/image-20160120-26079-1oltp03.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=470&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/108686/original/image-20160120-26079-1oltp03.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=470&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Note the pattern of sunlight through the wine glass.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/johnmelancon/4968918066/">Flickr/John Melancon</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-sa/4.0/">CC BY-NC-SA</a></span>
</figcaption>
</figure>
<p>That pattern is the light from the sun being focused and defocused by refraction through the wine glass. As you move though the pattern, you see the sun as brighter or fainter, depending on whether you’re closer, or further from the focus of the glass.</p>
<p>That’s exactly what we have with these blobs, but scaled up to cosmic scales. The radio waves from the quasar shine through the blobs, which act as an interstellar lens and which then makes a pattern in space. As the Earth moves through the pattern, the quasar appears brighter or fainter.</p>
<h2>What shape are the blobs?</h2>
<p>Now here’s where it gets interesting. If one assumes the lenses are spherical balls of plasma (think meatball), one can calculate that the cloud is so highly over-pressured, it should quickly disperse.</p>
<p>How, then, are the clouds held together long enough for us to see them? A sheet of plasma (like lasagne) viewed edge-on solves this problem, by spreading the plasma out over a large distance. </p>
<p>Another, intriguing proposal, is that the lenses are cold clouds surrounded by a shell of plasma (like a hazelnut). If these cold clouds are held together by their own gravity, then they must be pretty massive. If this is the case, then these cold clouds could represent a substantial fraction of the missing baryons in our galaxy.</p>
<h2>A new technique</h2>
<p>Before our work, only a handful of events had been discovered with old telescopes, and mostly on an ad-hoc basis using archival data obtained for other purposes. The traditional approach, called the light curve method, looked at the brightness of a few hundred quasars roughly every day at one or two different radio frequencies.</p>
<p>It’s helpful to think of these old telescopes like your car radio: you can listen to only one radio station at a time. If you want to listen to another radio station, you have to turn the dial. If you want to find a plasma lens, you have to come back to that quasar every day, to see if it’s changed.</p>
<p>But, there’s a better way. Let’s get back to the wine glass. If you look closely at the pattern on the table, you’ll see that the white light from the sun is also split into different colours by the glass: which means that some parts of the pattern will have a redder tinge, and some a bluer tinge.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/108687/original/image-20160120-26113-bezcec.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/108687/original/image-20160120-26113-bezcec.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/108687/original/image-20160120-26113-bezcec.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=364&fit=crop&dpr=1 600w, https://images.theconversation.com/files/108687/original/image-20160120-26113-bezcec.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=364&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/108687/original/image-20160120-26113-bezcec.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=364&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/108687/original/image-20160120-26113-bezcec.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=458&fit=crop&dpr=1 754w, https://images.theconversation.com/files/108687/original/image-20160120-26113-bezcec.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=458&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/108687/original/image-20160120-26113-bezcec.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=458&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Note the differing colours from the light through the wineglass.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/anataman/72105466/">Flickr/anataman</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
</figcaption>
</figure>
<p>If we’re in a certain part of the pattern, instead of seeing white light coming from the quasar, we see some colours more strongly focused than others. All we needed was a telescope that could tune not to a single radio station at a time, but all the radio stations at the same time.</p>
<p>Fortunately, we have this wonderful machine: the <a href="https://www.narrabri.atnf.csiro.au/">Australia Telescope Compact Array</a>, at Narrabri in rural New South Wales. With the the Compact Array, we don’t get just two channels for every measurement, we get 9,000 channels. </p>
<h2>Excited observations</h2>
<p>When we found our event, we were super excited. Not only had our idea worked, but it felt like we’d seen colour TV for the first time, after living with black and white for more than 20 years!</p>
<p>We also knew the game was on and we had to act fast. So we pointed a few other telescopes to see what we could see. First, we got the <a href="http://www.gemini.edu/">Gemini</a> 8m telescope in Chile, and a <a href="http://www.astro.yale.edu/smarts/1.3m.html">1.3m</a> telescope, also in Chile, to monitor the brightness of the quasar in optical light.</p>
<p>We didn’t expect the plasma to do anything to optical light, but we thought there might be dust in the lens that might tell us what it’s made of. We didn’t see any dust, which is also interesting from the dark matter standpoint: previous surveys for Massive Compact Halo Objects (MACHOs) in the optical never saw any dusty lenses either.</p>
<p>The second pair of telescopes were radio telescopes, but spaced all over <a href="http://www.atnf.csiro.au/vlbi/overview/index.html">Australia</a>, and the <a href="https://public.nrao.edu/telescopes/vlba">US</a>. These telescopes use a technique called <a href="http://earthsky.org/astronomy-essentials/how-vlbi-reveals-the-universe-in-amazing-detail">Very Long Baseline Interferometry</a> (VLBI) to make the most detailed possible images of the sky (even better than the Hubble Space Telescope).</p>
<p>We expected to see the quasar wavering around (look at a light globe through a wine glass and you’ll see what I mean), but we didn’t see as much as we’d hoped.</p>
<p>What does it all mean? Well, some clever modelling by my colleagues <a href="http://manlyastrophysics.org/AboutUs/Affiliates/Tuntsov.html">Artem Tuntsov</a> and <a href="http://manlyastrophysics.org/AboutUs/ResearchCommittee/Walker.html">Mark Walker</a>, at <a href="http://manlyastrophysics.org/">Manly Astrophysics</a>, showed that the lens was either flat, like a sheet of lasagne, or hollow, like a hazelnut or noodle. It definitely wasn’t a bent sheet, and definitely not filled in the middle, like a meatball.</p>
<p>But is it the missing baryons? Well, it’s too early to tell. Pinning down the geometry using the VLBI is the Holy Grail right now.</p>
<p>The future of this work lies in CSIRO’s Australian Square Kilometre Array Pathfinder (<a href="http://www.atnf.csiro.au/projects/askap/index.html">ASKAP</a>), which will detect tens of lenses per year. With those lenses, we’ll be busy measuring shapes and chemical compositions. A large number of detections will yield the first in-depth study of the distribution of lenses over the sky.</p>
<p>Such measurements represent a huge leap in our understanding these lenses, a better understanding of the gas conditions in the interstellar medium, and maybe even a solution to the missing baryon problem.</p><img src="https://counter.theconversation.com/content/53442/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Keith Bannister 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 may have found evidence within our galaxy of some of the missing matter thought to make up our universe.Keith Bannister, Astronomer, CSIROLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/41532011-11-03T19:34:49Z2011-11-03T19:34:49ZIs life on Earth due to a quirk in the laws of physics?<figure><img src="https://images.theconversation.com/files/5158/original/6032588644_eb9f6841ef.jpg?ixlib=rb-1.1.0&rect=4%2C14%2C450%2C399&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">If the signs are right, fundamental equations of cosmology may need altering.</span> <span class="attribution"><span class="source">waljoris</span></span></figcaption></figure><p>A radical discovery by my colleagues and I – reported this week in <a href="http://prl.aps.org/abstract/PRL/v107/i19/e191101">Physical Review Letters</a> – could help explain why it was possible for life (at least as we know it) to develop on Earth, but not in other parts of the universe.</p>
<p>It suggests one of the fundamental laws of physics, <a href="http://myfundi.co.za/e/Electromagnetism:_Overview">electomagnetism</a>, is not constant throughout the universe and may change depending on where you are. </p>
<p>Big claims? Yes, they are. The discovery we have made is radical. Onlookers are skeptical and it may take years to show whether we are right or wrong. </p>
<p>And, yes, who am I to speak?</p>
<p>I lead a <a href="http://www.phys.unsw.edu.au/%7Ejkw/alphadipole_media/alphadipole_media/Welcome.html">research group</a> at the University of New South Wales focusing on one very specific question: have the laws of physics always been as we know them today on Earth, or were they different in the early universe. My work sits at the boundary between fundamental physics and astronomy. </p>
<p>In general terms, I investigate what the universe was like when it was very young and how it has evolved over the 14 billion years since it spontaneously appeared.</p>
<h2>Light fantastic </h2>
<p>When my colleagues and I looked at the spectra of gas clouds in the early universe and compare with the same elements measured in laboratories on Earth, we saw very slight but significant differences. </p>
<p>A simple analogy might help explain this:</p>
<p>Consider a barcode on an every-day item on a supermarket shelf. </p>
<figure class="align-right ">
<img alt="" src="https://images.theconversation.com/files/5162/original/gnews_pics.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/5162/original/gnews_pics.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=469&fit=crop&dpr=1 600w, https://images.theconversation.com/files/5162/original/gnews_pics.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=469&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/5162/original/gnews_pics.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=469&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/5162/original/gnews_pics.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=589&fit=crop&dpr=1 754w, https://images.theconversation.com/files/5162/original/gnews_pics.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=589&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/5162/original/gnews_pics.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=589&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption"></span>
<span class="attribution"><span class="source">gnews pics</span></span>
</figcaption>
</figure>
<p>The relative positions of the strips in the barcode form a unique identifier to the item in question. Similarly, in the spectra of distant gas clouds, we see distinct lines caused by various elements such as magnesium, iron, aluminium, nickel, chromium, zinc and many others. </p>
<p>We can visualise the spectrum of this gas just as we do with the barcode, where the relative positions of the lines uniquely identify the elements present. </p>
<p>These relative positions in the distant cloud of gas can be measured with impressive precision and what we have found is amazing: the unique patterns of lines for the same elements seen in laboratory measurements today are slightly different to that seen in distant galaxy halos. </p>
<p>In fact, when we make measurements of this sort, it turns out we are actually measuring electromagnetism, the force that binds electrons and nuclei together in atoms. This is because relative positions of the lines in the spectrum are determined by the strength of the electromagnetic force. </p>
<p>We only know of four forces in nature: electromagnetism, gravity, and the strong and weak forces acting within atomic nuclei themselves. And at least one of them, in other regions of the universe, now appears to be different from that on Earth.</p>
<p>But the story gets stranger still. </p>
<p>My colleagues and I have looked out into the universe all over the sky, probing physics in 300 different places. We’ve found the strength of electromagnetism changes gradually from one “side” of the universe to another – a slow spatial gradient in physics.</p>
<p>The implications for science are profound. All “textbook” physics rests on the assumption of constancy of the laws of physics. One example is <a href="http://theconversation.com/explainer-einsteins-theory-of-general-relativity-3481">Einstein’s theory of general relativity</a>, which embodies this assumption in something called the “<a href="http://science.nasa.gov/science-news/science-at-nasa/2007/18may_equivalenceprinciple/">Equivalence Principle</a>”. </p>
<p>If my colleagues and I are right, this may now need to be demoted to the “Equivalence Approximation”. The fundamental equations of cosmology may need altering, with important re-interpretations for a multitude of experimental data, potentially even including the seemingly mysterious “<a href="http://theconversation.com/adventures-in-the-dark-side-of-cosmology-1455">dark energy</a>”, which is currently thought to provide 70% of the energy content of the universe, even though its nature is entirely unknown.</p>
<h2>How we got here</h2>
<p>Some 11 years ago, my Russian colleague <a href="http://www.phys.unsw.edu.au/STAFF/ACADEMIC/flambaum.html">Victor Flambaum</a> and I made a breakthrough. We came up with an idea that allowed us, literally overnight, to improve the precision with which we could measure the physical laws elsewhere in the universe by a factor of 10. </p>
<p>We named this new method, perhaps unattractively, the “Many-Multiplet” method. It has now become the default technique used by most competing research groups in universities around the world.</p>
<p>We applied the new idea to astronomical observations of distant <a href="http://csep10.phys.utk.edu/astr162/lect/active/quasars.html">quasars</a>. </p>
<p>Quasars are relatively small objects in astronomical terms, probably about the <a href="http://theconversation.com/long-way-to-the-chemists-a-rough-guide-to-distances-in-the-universe-2154">size of the solar system</a>, or less than 1000th the size of a galaxy. </p>
<figure class="align-left ">
<img alt="" src="https://images.theconversation.com/files/5163/original/NASA_Goddard.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/5163/original/NASA_Goddard.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/5163/original/NASA_Goddard.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/5163/original/NASA_Goddard.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/5163/original/NASA_Goddard.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=502&fit=crop&dpr=1 754w, https://images.theconversation.com/files/5163/original/NASA_Goddard.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=502&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/5163/original/NASA_Goddard.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=502&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
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<span class="attribution"><span class="source">NASA/Goddard</span></span>
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<p>And yet they are the most energetic objects known in the universe. They emit as much as a thousand billion times the energy of our sun. This energy is generated by the efficient conversion of matter into energy according to the Einstein’s well-oiled <a href="http://www.worsleyschool.net/science/files/emc2/emc2.html">E=mc<sup>2</sup></a> equation. </p>
<p>That means quasars can be seen at enormous distances, and we can study them in great detail using the worlds’ biggest telescopes – the <a href="http://www.keckobservatory.org/">Keck telescope</a> in Hawaii and the <a href="http://www.eso.org/public/teles-instr/vlt.html">Very Large Telescope</a> in Chile. </p>
<p>By employing such high-precision instrumentation, we can use the spectrum of the quasar to measure the detailed physical conditions in the galactic gas intersecting the sight line to the background quasar.</p>
<h2>Fine-tuning</h2>
<p>Another interesting consequence concerns the so-called “<a href="http://theconversation.com/peer-review-the-fallacy-of-fine-tuning-2540">fine-tuning</a>” problem. For decades, scientists have puzzled over the fact that the laws of physics seem to be mysteriously tuned to favour our existence. </p>
<p>No explanation at the fundamental level exists. The “hand of God” is preferred by some as the explanation for fine-tuning. Others prefer the “<a href="http://www.anthropic-principle.com/primer.html">Anthropic Principle</a>”: we shouldn’t be surprised to find the universe is apparently finely-tuned for our presence in it, otherwise we wouldn’t be here to discuss the matter in the first place. </p>
<p>Our observed values of the laws of physics are then put down to mere chance.</p>
<p>But if the laws of physics gradually change from one region of the universe to another, it may simply be that we happen to reside in that part of the universe where the local “by-laws” are perfect for life as we know it. </p>
<p>Elsewhere, that may not be the case and the universe may be radically different, with a different periodic table, different chemistry and biology, or even no biology at all. </p>
<p>And since we see only a very small change in the strength of electromagnetism over cosmological scales, that change may continue unabated for a spatial eternity. In other words, space is infinite. This is my preferred interpretation.</p>
<p>As I said at the start of this article, no-one believes us yet, and we are in for a long battle. Some days I doubt I shall be living when the proof comes in. </p>
<p>The work is technical, laborious, very difficult, requires a great deal of data from extremely expensive scientific facilities, and the analyses take a lot of time and effort. </p>
<p>But on other days I’m more optimistic and remind myself that, for now, I’m alive and kicking and working on it.</p><img src="https://counter.theconversation.com/content/4153/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>John K. Webb 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>A radical discovery by my colleagues and I – reported this week in Physical Review Letters – could help explain why it was possible for life (at least as we know it) to develop on Earth, but not in other…John K. Webb, Professor of Astrophysics, UNSW SydneyLicensed as Creative Commons – attribution, no derivatives.