Multiple Black Holes

[Mespo_Man]

1) Is there any reason why a galactic center could not contain more than one black hole?

2) If multiple black holes are possible, is there any reason why they couldn't orbit each other like binary stars or even form a "solar system" of several mini-black holes orbiting around the BBK? (Big Black Kahoona)

(:raig

[JS Princeton]

There is, in principle, no reason that you can't have two black holes orbitting one another. However, given enough time all orbits will degrade and they will eventually spiral in towards each other. As we believe that galactic center black holes have been around for quite some time, you are less likely to find this type of combination. This will leave you with one supermassive black hole. I should note, though, that the theory isn't altogether clear on how these blackholes end up at the centers galaxies. Stay tuned.

Once you get one blackhole you can't split it up.

[segfault]

On 2002-11-13 13:19, JS Princeton wrote:
There is, in principle, no reason that you can't have two black holes orbitting one another. However, given enough time all orbits will degrade and they will eventually spiral in towards each other. As we believe that galactic center black holes have been around for quite some time, you are less likely to find this type of combination. This will leave you with one supermassive black hole. I should note, though, that the theory isn't altogether clear on how these blackholes end up at the centers galaxies. Stay tuned.

Once you get one blackhole you can't split it up.

I don't have the link handy, but I was just looking at some images generated from radio telescopes and unless I was looking at the images or reading the summaries wrong (quite possible) - some of the images of active galactic nuclei quite clearly show double-nucleus galaxies, which possibly means 2 supermassive black holes if some current theories are on the mark.

That's obviously on a very large scale, but I guess it still counts as double black hole I suppose.

But hypothetically speaking, if you had a binary star system, with both stars having enough mass to go supernova and turn into black holes, what are the chances of ending up with a binary blackhole system?

I'd assume that unless both stars went supernova pretty close to each other, the first one to blow up would either blast the other star into little bits and pieces, or the gravitational pull from the newly-formed black hole would siphon off gas from the companion star to the point where it no longer had enough mass to go supernova anymore.

[JS Princeton]

I think most of the "double nuclei" galaxies are theorized to be the result of a recent galaxy collision (or galactic canabalism, if you like).

[David Hall]

Speaking of which, our nearest (major) galactic neighbor, Andromeda, seems to have a double nucleus.

http://antwrp.gsfc.nasa.gov/apod/ap961011.html

I wonder if double nuclei generally have 2 black holes, one in each nucleus?

[aporetic_r]

Please excuse my ignorance, but what exactly would happen when the orbits of 2 black holes degraded and they finally collided? I can't imagine there being any sort of conventional explosion.

[Kaptain K]

On 2002-11-17 16:01, aporetic_r wrote:
Please excuse my ignorance, but what exactly would happen when the orbits of 2 black holes degraded and they finally collided? I can't imagine there being any sort of conventional explosion.

You get a single black hole with a very high spin rate.
There would be an extremely energetic outpouring of EM from the collision of the accretion disks

[RafaelAustin]

Wouldn't there be an enormous burst of gravity waves too? It seems like this is the kind of event that astrophysicists are looking for to prove gravity waves and gravitons.

[Zathras]

On 2002-11-18 12:00, RafaelAustin wrote:
Wouldn't there be an enormous burst of gravity waves too? It seems like this is the kind of event that astrophysicists are looking for to prove gravity waves and gravitons.

Yes, black holes rotating around each other would be the best possible place for detecting gravity waves. We'll just have to wait and see...