Black Hole Sans Donut Puzzles Astronomers

Anonymous Squonk writes: "This time, a telescope made news by not finding something. According to this Honolulu Star-Bulletin article, a black hole was found that did not contain the expected 'donut' of warm matter swirling around it. This discovery (or lack of discovery) may lead scientists to rethink what they know about the core of active galaxies."

Comments

This is about torus, not the disk

[Caid Raspa]

\begin{rant}
If you see 'theory + astronomy + black hole' this does not automatically mean theory==relativity.
RTFA
\end{rant}

It is so massive that its event horizon is far enough away from the center so that the tidal forces are not enough to produce the large, flattened disk of hot spiraling matter

The 'flattened disk' you refer to is the accretion disk that is easily seen in M87. For example, the X-ray spectrum would be completely different if there was no disk.

The 'doughnut' or torus is a cloud of cool matter, that is feeding the disk. It is about just as 'flat' as a real doughnut. Generally the torus of an average active galaxy is far enough from the black hole to make all relativistic effects insignificant. Relativity is very important at the inner edge of the accretion disk, where the disk meets the event horizon. However, this is literally light-years from the torus.

Now, the astronomers can not see the torus. This means that the matter fed to the black hole is almost finished, and should not be able to power such a bright accretion disk. I believe this is the 'problem'.

Either the accreted matter comes from some unknown source, and/or some mechanism makes the accretion disk brighter than expected. Thus theoretical problems are more probably related to galaxy evolution and/or accretion disks. These are both rather ill-understood issues when compared to general relativity.

Re:Is it my imagination...

[Lowther]

It isn't your imagination. Astrophysicists don't know - they are making a best guess on the limited information they have available. Just a matter of a few hundred years ago, we were prepared to throw a man in jail because he declared his belief that the Earth circled the Sun, and not vice versa. At that time it was also a matter of debate as to whether the planet was a sphere (or oblate spheroid even), or whether it was flat. And we were living on it at the time !

Given the fact that our technology will only allow us to venture a miniscule distance from our planet in universe terms, and achieving more will take centuries (if we survive that long), and at best we can observe but a miniscule fraction of it from our planet, and it is supposed to be growing, it follows that we know nothing of the universe, and this will not change in our lifetimes or our children's.

And yes, massive amounts of funding are tied up in this exploration. We need to explore the universe. But if the astrophysicists said "Well chaps, we have looked into the skies for centuries, spent trillions on manned and unmanned missions, and, to tell the truth, we still know jack s**t", I suspect the funding would dry up. It is better for them to present each new discovery as something which enhances and expands our comprehension, and challenges our hypotheses, rather than admitting that in real terms, we still know nothing about the Universe and how it works.