Two black holes in M22 discivered

[bojan]

It seems there was a controversy about existence of more than 1 BH in one globular cluster..
It's a bit surprising for me because there are number of pulsars found in globulars.. so why not BH? (well.. those are pretty massive, but still...)

http://scienceblogs.com/catdynamics/2012/10/03/cohabiting-black-holes-in-m22/
http://www.stuff.co.nz/science/7769386/Double-black-hole-discovery
http://news.discovery.com/space/black-hole-twins-121003.html

[mental4astro]

I wouldn't be surprised if BH's are more common than we may think. If we look at it simply, they are nothing more than gargantuan stars, remnant cores or otherwise.

If memory serves me right, most BH's are small, unstable and short lived. They could well have been a lot more common earlier in the Universe' history when super massive stars were much more common too due to the higher density of matter, etc.

Are there not also super massive stars that are invisible to our eyes as they glow in the UV spectrum they are so hot? I could be mistaken here though.

These two BH's interplay should provide for very interesting study.

[bojan]

The difference with pair of BH's is, if they are mutually interacting in in very close proximity, relativity effects start to play tricks, resulting in unstable orbits, long term (unlike with Newtonian gravity where orbits are stable - unless there are more than two players).

But if they are not too close, relativity effects are the same as for stars.. so that is why I am puzzled by those controversies mentioned in links I provided earlier.

[Dave2042]

Not speaking as an expert, but isn't the point that they are in a globular cluster?

As I understand it, GC's are extremely old. This means that they have had a very long time for massive objects to fall toward their center, hence their spherical appearance, with high star density concentrated, in the center and heavily dependent on radius. The expectation then would be that black holes would have long since grown large, fallen to the center and coalesced. The fact that this hasn't happened is a bit odd.

As I understand it, the degree to which we don't understand how black holes interact with their surroundings is already fairly high. Last time I checked, we still don't understand how galactic central black holes can swallow enough material to produce typical radio jets - too much angular momentum in the orbiting material and no obvious way of getting rid of it.

[LAW]

http://www.youtube.com/watch?v=wy-C5kI4jGs

;)

[ourkind]

Nice one :thumbsup: