Sections

Services

Information

UK United Kingdom

NASA puts new spin on black holes

Scientists in the US have successfully used a new NASA telescope to help improve our understanding of how black holes and…

The reflected light from black holes enables astronomers to see how fast matter is swirling in the inner region of the disk, and ultimately to measure the black hole’s spin rate. NASA/JPL-Caltech

Scientists in the US have successfully used a new NASA telescope to help improve our understanding of how black holes and galaxies evolve. Using data taken by the Nuclear Spectroscopic Telescope Array, or NuSTAR, and the European Space Agency’s XMM-Newton X-ray satellite, scientists were able to measure the spin rate of a black hole with a mass 2 million times that of our sun.

NASA said the observations, which are published in the journal Nature, provide a powerful test of Einstein’s theory of general relativity, which says gravity can bend space-time, the fabric that shapes our universe, and the light that travels through it.

“We can trace matter as it swirls into a black hole using X-rays emitted from regions very close to the black hole,” said NuSTAR principal investigator Fiona Harrison of the California Institute of Technology. “The radiation we see is warped and distorted by the motions of particles and the black hole’s incredibly strong gravity.”

A similar experiment was undertaken in 2006, said Geraint Lewis, professor of astrophysics at University of Sydney. “But there was a worry intervening gas could have distorted the shape of the emission and therefore we weren’t accurately measuring the spin.” Professor Lewis said the new research found that the measurements wouldn’t have been so badly affected. “It’s confirmed that these black holes are spinning and they’re spinning very fast.”

The researchers said while XMM-Newton revealed that light from the iron was being warped, NuSTAR proved that this distortion was coming from the gravity of the black hole and not gas clouds in the vicinity. “The next thing they surely will do now is go and look at a range of galaxies to see if they can measure the spin there,” Professor Lewis said. “If we found a large number that weren’t spinning it would be a serious problem for our understanding of the galaxy.”

“This is hugely important to the field of black hole science,” said Lou Glassiness, a NuSTAR program scientist at NASA Headquarters in Washington.

Sign in to Favourite

Join the conversation

7 Comments sorted by

    1. Stephen McCormick

      Ph.D. Candidate at School of Mathematical Sciences, Monash University

      In reply to Riddley Walker

      [Warning: My background is in the mathematics of these things, so an astrophysicist's explanation would likely be more complete; but this is my understanding]

      It would almost be stranger if things were so perfectly balanced that they didn't rotate. But the reason that black holes spin so fast is because angular momentum is conserved; try spinning on an office chair slowly with your body outstretched, then curl up into a ball on the seat. You'll notice that you immediately spin faster because your mass is closer to the axis of rotation. Now imagine something 2 million times as massive as our sun compressing itself into something tiny; even if it only appeared to be slowly rotating before the collapse, it would be spinning pretty damn fast afterwards.

      report
    2. Riddley Walker

      .

      In reply to Stephen McCormick

      Thank you, that does help - I understand that theory I just didn't get what gets the whole thing going, if you get my drift. But apparently just a little drift is enough? Plus gravity?

      report
    3. Stephen McCormick

      Ph.D. Candidate at School of Mathematical Sciences, Monash University

      In reply to Riddley Walker

      My astrophysics is definitely lacking, so again, take anything I say on this topic with that caveat.

      As I understand it, stars form from large amounts of small things floating around in space - space dust of sorts - gathering together due to their mutual gravitational attraction. As the space dust becomes more and more compressed, it should heat up and it may eventually undergo nuclear fusion. Wikipedia likely has a far better explanation than me for that. But anyway, the point is, the original…

      Read more
  1. Doug Hutcheson

    Poet

    So, what is the diameter of the studied black hole and how fast is it spinning?

    report
    1. Stephen McCormick

      Ph.D. Candidate at School of Mathematical Sciences, Monash University

      In reply to Doug Hutcheson

      My "back-of-the-envelope" calculation says it's about 30 million km in diameter (the event horizon) with 3*10^56 Nms of angular momentum. I have no feel for what's normal for these things though, so I can't be certain that's right...

      Anyway, the interesting thing - I think - is that there's a theoretical limit on how much angular momentum a black hole can have, relative to its mass; this particular one appears to have 84% of its maximum theoretical angular momentum. (That's the number quoted in the Nature paper, nothing to do with my calculations)

      report