• Due to ongoing issues caused by Search, it has been temporarily disabled
  • Please excuse the mess, we're moving the furniture and restructuring the forum categories
  • You may need to edit your signatures.

    When we moved to Xenfora some of the signature options didn't come over. In the old software signatures were limited by a character limit, on Xenfora there are more options and there is a character number and number of lines limit. I've set maximum number of lines to 4 and unlimited characters.

Researchers spot black hole feeding at 40 times its theoretical limit

Puppycow

Penultimate Amazing
Joined
Jan 9, 2003
Messages
29,826
Location
Yokohama, Japan
I thought this was interesting:

Researchers spot black hole feeding at 40x its theoretical limit (Ars Technica)

With the advent of the Webb Space Telescope, the problem has pushed up against theoretical limits. The matter falling into a black hole generates radiation, with faster feeding meaning more radiation. And that radiation can drive off nearby matter, choking off the black hole's food supply. That sets a limit on how fast black holes can grow unless matter is somehow fed directly into them. The Webb was used to identify early supermassive black holes that needed to have been pushing against the limit for their entire existence.

This "theoretical limit" is called the Eddington Limit, but it doesn't seem to actually hold true. It does seem to solve the problem of how supermassive black holes came to be so massive, so soon after the Big Bang.
 
Has a black hole actually been "spotted" feeding at 40 times the theoretical limit?

It sounds more like a black hole has been spotted that is larger than it possibly could be given the assumed age of the universe at its redshift.
 
The article says based on it's mass and luminosity, that this black hole is actually feeding at 40 times the limit.
 
Has a black hole actually been "spotted" feeding at 40 times the theoretical limit?

It sounds more like a black hole has been spotted that is larger than it possibly could be given the assumed age of the universe at its redshift.
There are lots of assumptions that have been made about how supermassive black holes evolve and grow. But observations seem to throw doubt on such models. This observation, for example, appears to show that the "Eddington Limit" isn't really a limit. There's also one called the final parsec problem (which is a problem in the models, probably not in reality) which is that supermassive black holes according to the models wouldn't actually merge with each other once they get as close as about a parsec (or about 3 light years) from each other, and instead would just basically orbit each other (or their common barycenter) without getting any closer in most cases.

I think what it shows is that the models based on current assumptions are incomplete and do not adequately model all influences.
 
There's also one called the final parsec problem (which is a problem in the models, probably not in reality) which is that supermassive black holes according to the models wouldn't actually merge with each other once they get as close as about a parsec (or about 3 light years) from each other, and instead would just basically orbit each other (or their common barycenter) without getting any closer in most cases.

Your link wasn't very clear about the nature of the problem. In particular, on reading it I couldn't figure out why they weren't discussing gravitational waves, and I was left wondering why that wasn't the solution, since gravitational wave do bleed of absurd amounts of energy in black hole mergers. The Wikipedia page does a better job of explaining the problem. In particular, there's a gap between where above the gap we expect other matter to act in slowing down their orbit, and below the gap gravitational waves kick in, but in that gap they're too close for there to be enough matter between them to act as a brake (at least in our models), but too far apart for gravitational waves to have any significant effect.

I think what it shows is that the models based on current assumptions are incomplete and do not adequately model all influences.

Yes, that's almost certainly the case.

I remember about 30 years ago, a friend of mine was asking me about a news story that said that astronomers found globular clusters older than the age of the universe, and he was asking me how that was possible. The answer of course is that it's not possible. But the news story didn't really convey that the problem wasn't figuring out how the globular cluster could be older than the universe, but rather that there was a conflict between the methods we use for measuring the age of the universe and the methods for measuring the age of globular clusters. One (or both) of those methods must be wrong. And given that our methods for measuring the age of globular clusters are much more speculative, it's a safe bet that all that was going on was that we were wrong about how we measured globular cluster age. Which is interesting, but far less sensational than globular clusters actually predating the big bang. So the news story naturally went with the sensational but wrong interpretation.
 
I think they should rename it the Penultimate Parsec Problem. Both for the alliteration, and because it's not actually the final distance to close before merger. The final (ultimate) distance to close is closed by losing energy to gravitational waves, we know that part pretty well. It's the second to final distance, the penultimate distance that we don't understand how to close.
 
PBS Space Time just made an episode about LID-568 and it's feeding at 4000 times the Eddington Limit.

ETA: I think they made an embarrassing mistake. The thumbnail says 4000% as suggested in the OP.

 
Last edited:
Back
Top Bottom