10,000 black holes near Sagittarius A ?

[phinds]

Interesting sidebar in The Week (April 27, 2008, page 20) referencing a BBC.com news items (yeah, I know this is pretty indirect) that says a dozen binary pairs of black hole with orbiting stars have been identified near Sagittarius A by the Chandra X-ray Telescope. They go on to say

Because binary systems account for only a small proportion of black holes overall, they calculated that 10,000 other black holes must be lurking in the same area

and that the galactic center is a hothouse for black hole formation.

I can't find the BBC.com article so I have no further reference but I wonder if anyone here knows anything further about this?

Oh, and I should add that the binary pairs are stated as being "within a few light years of Sagittarius A", so not exactly right next door.

 

[kimbyd]

It doesn't sound unreasonable to me. The real problem is defining precisely what is meant by "galactic center". It would be pretty easy to come up with a definition that includes many millions of stars, perhaps even a billion. And as it would be reasonable to assume that the most massive stars would be more likely to form near the galactic center, it is likely to be rather richer in black holes than most of the galaxy.

In sum, the statement that there are 10,000 black holes near the galactic center is meaningless without understanding what is meant. And as it sounds like the estimate came not from a scientific paper, but from a back-of-the-envelope calculation, it's going to be difficult to track down precisely what the statement means.

 

[phinds]

And as it sounds like the estimate came not from a scientific paper, but from a back-of-the-envelope calculation, it's going to be difficult to track down precisely what the statement means.

Right. That's why I'm asking here if anyone has more information on it. It DID apparently come from some kind of scientific study (I suspect it can be traced back to a NASA report) but as you say, the level of rigor is utterly indeterminate.

 

[JMz]

An arguably relevant link: https://apod.nasa.gov/apod/ap060729.html
No sources cited, and the BH identifications are ambiguous. OTOH, it's only three LY from Sgr A*.

 

[EmileJ]

I think it was based on an article in Nature:

A density cusp of quiescent X-ray binaries in the central parsec of the Galaxy

https://www.nature.com/articles/nature25029

 

[kimbyd]

An arguably relevant link: https://apod.nasa.gov/apod/ap060729.html
No sources cited, and the BH identifications are ambiguous. OTOH, it's only three LY from Sgr A*.

Nice. There's a preprint linked there:
https://arxiv.org/abs/astro-ph/?0412492

Within one parsec is incredible. That's a little less than the distance between our solar system and the next nearest star system (Proxima Centauri).

 

[cosmik debris]

Sounds like a Beatles song to me only the holes were in Blackburn.

Cheers

 

[JMz]

Nice. There's a preprint linked there:
https://arxiv.org/abs/astro-ph/?0412492

Within one parsec is incredible. That's a little less than the distance between our solar system and the next nearest star system (Proxima Centauri).

And thus we have crowd-sourced our way to an answer (with a very small crowd). :-)

 

[newjerseyrunner]

PBS Spacetime just did a video about the paper. The team basically found 13 X-ray points that matched the spectra of black hole-star binaries within a parsec of the galactic center. They extrapolated from the expected ratio between these types of black holes and the rest to get an approximation around ten thousand.

 

[phinds]

PBS Spacetime just did a video about the paper. The team basically found 13 X-ray points that matched the spectra of black hole-star binaries within a parsec of the galactic center. They extrapolated from the expected ratio between these types of black holes and the rest to get an approximation around ten thousand.

Very lucid explanation. Thanks for posting.

 

[JMz]

[/QUOTE]
I second @phinds' response: Thanks.