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Monster Black Hole Busts Theory

Posted by samzenpus on from the old-bob-and-vincent dept.

Genocaust writes "A stellar black hole much more massive than theory predicts is possible has astronomers puzzled. Stellar black holes form when stars with masses around 20 times that of the sun collapse under the weight of their own gravity at the ends of their lives. Most stellar black holes weigh in at around 10 solar masses when the smoke blows away, and computer models of star evolution have difficulty producing black holes more massive than this. The newly weighed black hole is 16 solar masses. It orbits a companion star in the spiral galaxy Messier 33, located 2.7 million light-years from Earth. Together they make up the system known as M33 X-7."

4 of 248 comments (clear)

  1. Re:Supermassive black holes by StikyPad · · Score: 5, Interesting

    If theory says that black holes beyond 10 solar masses cannot form, how do they explain the conjectured supermassive black holes

    Like This.

    Or, more pedantically, black holes may never form at all from the point of view of an observer outside the event horizon.

    --
    https://www.eff.org/https-everywhere
  2. Computer models of Supernovae by confused_demon · · Score: 5, Interesting

    For this discussion it's worth keeping in mind that current computer models have real problems actually getting supernovae to explode. At one point it was so bad that I heard someone say, "If it weren't for the fact that we occasionally observe one explode, I would assure you that they cannot." It's only been in the last couple of years that someone has made a computer model that actually did it.

    1. Re:Computer models of Supernovae by Leperous · · Score: 4, Interesting
      "It's only been in the last couple of years that someone has made a computer model that actually did it."

      Not true. As a numerical relativitist, I can tell you that no decent 3D simulations of supernovae currently exist.

      Half the problem is that the physics is simply unknown - is it sufficient for your model to contain rotation, magnetic fields, and what about the equation of state of the plasma? Neutrinos are also thought to play an incredibly important role in the supernova explosion mechanism, and subsequent nucleosynthesis (and other processes) that go on during the supernova event itself. The other half is the sheer computing power to evolve your equations over decent time scales with enough resolution, not to mention making sure the numerical methods you employ work.

      There are plenty of groups who are currently working towards 3D evolutions without any neutrino transport, and I think some people have done neutrinos in 1D. Try checking out some of the work by Leibendorfer, for example.

      A quick run down of the supernova event though, since the article skims over it very lightly: heavy elements gradually build up at the core (nickel and iron especially), and nuclear fusion shuts down due to their high binding energies. As a result, outwards pressure ("thermal support") is lost, and at some critical moment the core will rapidly collapse onto itself (on a timescale of less than a second) as gravity becomes the dominant force. The outer layers will also in-fall onto this collapsing core.

      Depending on the mass of the star, we'd expect the core to collapse into some kind of 'proto' neutron star, or straight into a black hole, if it's massive enough. In the case of the former, neutrinos escaping from the cooling central proto neutron star deposit energy into the outer layers, and drive the actual supernova explosion-event. In the case of the latter, I'm not sure that you'd actually see much of a supernova since neutrinos wouldn't be able to escape from a black hole - or at least the explosion mechanism would be different. There is an 'intermediate' option though: a proto neutron star that later on collapses into a black hole, from the still in-falling outer layers. If this happens you'd expect both a black hole, and pretty violent supernova to boot.

      I'm not sure about the numbers presented in the article either. Typically, stars above 8 solar masses will collapse and create a supernova and neutron star remnant. Stars over 20 solar masses should form a neutron star which later collapses into a black hole (as is the case here). Stars over 50 solar masses or so will probably just collapse straight into a black hole, with unknown supernova mechanisms.

  3. Re:Supermassive black holes by ozbird · · Score: 4, Interesting

    A stellar black hole that's so big it shouldn't be possible for it to have been created by the usual supernova, and in a region of space sufficiently vacant to rule out the gobbling theory, is what is being puzzled over.

    The region of space is vacant now - it doesn't mean that it was when the black hole was feeling peckish.