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Largest Black Hole Measured

Posted by kdawson on from the that's-no-moon dept.

porkpickle tips us to a BBC article on the quasar OJ287, a binary object containing largest black hole yet discovered, weighing in at 18 billion times the mass of Sol. Researchers were able to estimate its mass due to the presence of a smaller black hole in orbit around it. When the smaller companion's orbit intersects OJ287's accretion disk, once every 12 years, it triggers a burst of radiation that was detected by the Spitzer Space Telescope. More detail and a diagram are available on the Turku University site.

8 of 170 comments (clear)

  1. eh? I don't get it? by Anonymous Coward · · Score: 4, Interesting

    How large can a singularity be?

    I mean, if they used the word "massive" I'd get it. But large?

  2. Question about gravity by caywen · · Score: 5, Interesting

    One question I have about gravity and black holes is this: If nothing can escape the event horizon, how can gravity escape it? In other words, would objects outside the event horizon ever feel the pull of gravity from that which is inside the event horizon?

    1. Re:Question about gravity by Anonymous Coward · · Score: 3, Interesting

      Gravitational pull isn't something that is being radiated out of bodies. Just changes of it.

      (In fact if the singularity somehow disappeared magically the outside world wouldn't detect it since the signal of black hole disappearing wouldn't escape from the gravitational well.)

    2. Re:Question about gravity by Ambitwistor · · Score: 2, Interesting

      However, the mediating particles themselves are not affected by the force they mediate. Otherwise the universe would disappear up its own arse.
      Hence, gravity is not affected by gravity. Actually, most mediating particles are affected by the force they mediate, including gluons, the hypothetical gravitons, and IIRC the W bosons.

      In gauge theory, a non-Abelian gauge group will in general lead to a nonlinear Yang-Mills theory with self-interacting fields, in contrast to the linear Abelian theory of electrodynamics.

      Because gluons, the mediator of the strong nuclear force, themselves carry strong ("color") charge, it's possible for them to bind to each other. (See glueballs in quantum chromodynamics.)

      Similarly, gravity gravitates: gravitons interact with each other, because they have energy and anything with energy gravitates. This idea holds even in classical general relativity: gravitational fields themselves gravitate. Analogously to QCD glueballs, general relativity can have gravitational geons, which are regions of gravitational field which hold themselves together under their own gravity. (You might think that a vacuum black hole has that property too, but I'm talking about purely non-singular field configurations.)
  3. Re:orbiting blackholes? by AbsoluteXyro · · Score: 2, Interesting

    It could be argued that the singularity of a black hole is an impossibly dense star. In which case, it would still be a solar system. However, it would only be a solar system if it had planets orbiting around it. It is highly unlikely that a black hole would have planets orbiting it, as the planets would have insufficient mass to keep from simply falling in to the black hole, that is to say the overwhelming mass of the black hole would place the barycenter of the black hole and any accompanying planet well inside the event horizon, and the orbital velocity that would be required to prevent simply being sucked in would be nigh unthinkable. A pair of black holes orbiting each other would be a binary system, just like two stars orbiting each other.

  4. Re:orbiting blackholes? by sentientbeing · · Score: 3, Interesting

    A holer system.

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    beware he who would deny you access to information, for in his mind he dreams himself your master
  5. Re:That's incredible! by cababunga · · Score: 2, Interesting

    Using same precise methods of measuring orbit axis and equation for calculating elliptic orbit http://en.wikipedia.org/wiki/Elliptic_orbit, 12 year period gives us speed 11k km/s in apoapsis and 64k km/s in periapsis. As I understand, with Lorentz transformation http://en.wikipedia.org/wiki/Lorentz_transformation 64k becomes 62.5k.

  6. Re:Now I don't get it! by Ambitwistor · · Score: 2, Interesting

    No. If you try to create gravitational waves (or light waves) and sent them back out through the horizon, they instead fall into the singularity (albeit more slowly than you yourself do as you fall, so you still see them traveling away from you).