Bubblecar said:
Here’s NASA on the subject.
On the Hunt for a Missing Giant Black Hole
https://www.nasa.gov/mission_pages/chandra/images/on-the-hunt-for-a-missing-giant-black-hole.html
Two obvious explanations.
1) Either the black hole is on a diet. A black hole of a diet can’t be seen by Candra or Hubble. This seems the most sensible explanation.
2) Or the black hole never existed in the first place. There’s no fundamental physical law that says that supermassive black holes must exist.
The hypothesis that gravitational waves pushed it out of the centre of the galaxy by “recoil” sound like pure rubbish to me. But I could be wrong.
quote=Tau.Neutrino
> Black Holes disappearing…
> Has this been discussed ?
New to me.
> Has a dust cloud, gas cloud, large object like a dark star / dead star / brown star been ruled out?
Pretty well, yes. A black hole generating X-rays isn’t easily obscured by a dust cloud or anything else.
> Are any more going to disappear?
This is a case of non-detection rather than disappearance. There could be quite a few others that can’t be detected.
> What would it take to cover both hemispheres for future disappearing black holes?
We’re talking supermassive black hole here. You’d need something that would block X-rays without turning those X-rays in to heat. Even a big thickness of rock won’t do that. A huge massively thick dust cloud perhaps. Much easier to clear all the debris away from the back hole’s environment. A black hole that doesn’t eat, doesn’t glow.
> Are they disappearing like quantum bubbles? If black holes are disappearing and particles pop in and out of existence according to quantum physics.
That would be on a totally different scale. If I understand correctly, virtual black holes can pop in and out of existence along with virtual electrons. But that’s tiny.
> Could this quantum bubble thing be bigger than we thought?
Not without swallowing the galaxy.
> Are black holes doing kind of the same thing but at a larger scale? Have any disappeared in the past?
Actually yes, but for galactic black holes on a timescale somewhere in the rough order of 10^67 years. The universe is only 1.38*10^10 years. So it won’t have happened even once in the whole history of the universe.
> What is the ratio (in size / scale) between quantum particles and black holes?
We’re considering supermassive (galactic) black holes here. Say 4.5*10^6 solar masses. The Sun is 2*10^30 kg. Quantum particles 10^-30 kg.
Multiply it out. Mass ratio 10^67.
LOL. That’s a peculiar coincidence with the answer to the previous question.
> Could past recordings be scanned for BHs disappearing?
We already have one, of a sort. Hanny’s Voorwerp is a light echo from a supermassive black hole that was much brighter 100,000 years ago.