Super-fast super-massive black hole spins at nearly light-speed
NuStar boffins peek through the clouds at NGC 1365
NuStar – the X-ray telescope launched by NASA last year – is turning in its first science with measurements revealing that the outer edges of the NGC 1365 black hole are spinning at 84 percent of light-speed or more.
The supermassive black hole in the NGC 1365 galaxy has a mass more than two million times that of the sun, but it’s the measurement of its accretion disk’s spin rate that’s impressive here.
There was already a suspicion, gleaned through observations made by the European XMM-Newton space telescope, that the black hole was something special. However, as the NuStar announcement states, estimates of the object’s spin rate may have been distorted by the huge amount of dust in the galaxy.
As matter in the accretion disk of a black hole falls in, it gives off X-rays; and the more massive the black hole, the smaller the accretion disk. This, in turn, means the X-rays are emitted from a spot closer to the gravity well, and therefore suffer more distortion.
Looking at NGC 1365, the astronomers focussed on X-rays emitted by iron in the accretion disk, combining observations from NuStar with others from Europe’s XMM-Newton space telescope.
This ESA image of NGC 1365 shows how much deeper NuStar is able to "zoom in" on the black hole
“With help from XMM-Newton, NuSTAR was able to see a broader range of X-ray energies and penetrate deeper into the region around the black hole. The new data demonstrate that X-rays are not being warped by the clouds, but by the tremendous gravity of the black hole,” the statement says.
With these more accurate measurements of the emitted X-rays, the astronomers were able to measure the Doppler effect caused by the black-hole’s rotation, revealing its relativistic speed. If The Register understands the detail in the astronomers’ paper in Nature (abstract here) correctly, the upper limit for the spin rate could be as much as 97 percent of light-speed.
As Phil Plait discusses here, there are a couple of possible explanations for the unbelievable speed: the black hole may simply have swallowed lots of matter that arrived at the right angle to add to its angular momentum; or a galactic collision could have turned two black holes into one with a huge boost to the spin on its accretion disk.
NASA has a set of visuals and videos here. ®
Re: That Ergosphere is gonna whip the wheels off Hawking's chair!
MATHS not MATH
MATH is what Americans do when designing spacecraft in a mixture of metric and imperial before launching it into a planet.
Re: WTF radiation?
>> First is that em-radiation is a duality - can be thought of as a particle or a wave. Particles are subject to gravity but waves are not. Therefore it is possible for radiation to escape (as a wave) but no THING escapes.
That's just fully wrong. For starters it assumes that one knows how to combine Quantum Field Theory and General Relativity. NOPE. Then is assumes that "particles" are "things" but "waves" (which should properly be called "fields", unless there is ANOTHER confusion) are not. NOPE. NOPE. NOPE.
> For a more accurate description you might like to find an advanced astrophysics textbook!
For any accurate description, you will have to await development in theoretical physics.
Meanwhile, hand-waving and finagling indicates that there is "Hawking radiation" which rests upon the idea you can have a quantum state in which a matter/antimatter pair (of whatever, just keep the sum of quantum numbers zero) is being "produced" at the edge at the event horizon (i.e. checking for particles has a non-zero probability of coming back positive) but one of the particles "disappears over the horizon" (finagle, wink, wink), while the other is observed laters far away from it. As the interpretation "the black hole emitted a particle" fits the observed history, one can take that.
Re: WTF radiation?
They don't*; this radiation is given off by the matter outside the black hole as it's falling in.
*except for Hawking radiation I guess