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Spinning Black Hole's Edge Rotates At Nearly the Speed of Light

Posted by Soulskill on from the you-must-be-this-tall-to-ride-the-black-hole dept.

astroengine writes "Astronomers have directly measured the spin of a black hole for the first time by detecting the mind-bending relativistic effects that warp space-time at the very edge of its event horizon. By monitoring X-ray emissions from iron ions (iron atoms with some electrons missing) trapped in the black hole's accretion disk, the rapidly-rotating inner edge of the disk of hot material has provided direct information about how fast the black hole is spinning. Astronomers used NASA's Nuclear Spectroscopic Telescope Array (NuSTAR) — that was launched into Earth orbit in June 2012 — and the European observatory XMM-Newton measured X-ray radiation as a tool to directly infer the spin of NGC 1365's black hole. 'What excites me is the fact that we are able to do this for the very massive black holes at the centers of galaxies but we can also make the same measurement for black holes in our galaxy ... black holes that resulted from the explosion of a star ... The fact we can extend this from billions of solar masses to 10 solar masses is pretty cool,' Fiona Harrison, professor of physics and astronomy at the California Institute of Technology, Pasadena, Calif., and principal investigator of the NuSTAR mission, told Discovery News."

7 of 227 comments (clear)

  1. know your audience by Anonymous Coward · · Score: 5, Funny

    i love how this summary explains what an ion is, but assumes i know the definitions of black hole, x-ray, and solar mass. great writing, folks!

    1. Re:know your audience by 140Mandak262Jamuna · · Score: 5, Funny

      Till I read the summary I thought ion is a iron with the letter r removed. Now I know what is removed is not r but electrons. Got it.

      --
      sed -e 's/Chuck Norris/Rajnikant/g' joke > fact
    2. Re:know your audience by nedlohs · · Score: 5, Insightful

      That's the point. It wastes a bunch of words explaining what an ion is.

      If you don't know what an ion is the rest of the words are going to make any sense anyway.

    3. Re:know your audience by smpoole7 · · Score: 5, Informative

      > I'm also astounded by the discovery of black holes resulting from an explosion of a star.

      Really massive stars (greater that 250 solar masses -- i.e., 250 times as massive as our own Sun) most assuredly do explode, and *very* violently, leaving behind a black hole. It's believed that this is a key source for gamma ray burst events. It's also thought that many of the first stars in the universe, not long after the Big Bang, exploded this way, spewing jets of metals at relativistic speeds.

      To be fair to you, it's now known that there are actually several different types of supernova. Some core collapses do occur without a big earthshattering "kaboom." The really massive stars explode due to photodisintegration, and result in a hypernova -- a ridiculously intense, you-don't-want-to-be-within-a-hundred-light-years kind of thingie. :)

      http://en.wikipedia.org/wiki/Photodisintegration

      http://en.wikipedia.org/wiki/Supernova

      --
      Cogito, igitur comedam pizza.
  2. Re:WRONG! by thechemic · · Score: 5, Funny

    I had a Honda Civic that could go the speed of light. It sucked because nothing ever showed up in the rear view mirror.

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    Let's make like a bird... and get the flock outta here.
  3. light is influenced by gravity by Anonymous Coward · · Score: 5, Informative

    http://helios.gsfc.nasa.gov/qa_sp_gr.html

    " Yes, light is affected by gravity, but not in its speed. General Relativity (our best guess as to how the Universe works) gives two effects of gravity on light. It can bend light (which includes effects such as gravitational lensing), and it can change the energy of light. But it changes the energy by shifting the frequency of the light (gravitational redshift) not by changing light speed. Gravity bends light by warping space so that what the light beam sees as "straight" is not straight to an outside observer. The speed of light is still constant."

    Dr. Eric Christian

  4. Re:Is the hole rotating, or just the disk? by Anonymous Coward · · Score: 5, Insightful

    By monitoring X-ray emissions from iron ions (iron atoms with some electrons missing) trapped in the black hole's accretion disk, the rapidly-rotating inner edge of the disk of hot material has provided direct information about how fast the black hole is spinning.

    So the summary indicates that measuring the accretion disk somehow tells them exactly how fast the non-emitting portion is spinning.

    The useful answer is in the link from the above quote:

    Risaliti and his colleagues measured X-rays from the center of NGC 1365 to determine where the inner edge of the accretion disk was located. This Innermost Stable Circular Orbit - the disk's point of no return - depends on the black hole's spin. Since a spinning black hole distorts space, the disk material can get closer to the black hole before being sucked in.

    So they calculated the spin of the black hole by comparing the observed orbit to the calculated orbits possible from the calculated mass based on observable gravitic effect on nearby objects. Yes, there's uncertainty there, but until someone discovers a new detail in astronomy, that's as accurate as we can get.