Matter and antimatter black holes colliding: annihilation or merger?

[Herbascious J]

What happens if two black holes of identical mass collide, but one is anti-matter and the other is regular matter? Would all of the matter anihilate in a gigantic explosion of photons which could be detected by a far away observer? Or, would all of the radiation energy, which would still have an enormous gravitational field equal to the combined energy of the two original black holes, remain trapped within the event-horizon of the now, merged, single black hole? This would be like a black hole made of nothing but photon energy (which I am assuming still warps space-time).

 

[Vanadium 50]

The two black holes would merge.

 

[yenchin]

In classical GR, according to the No-Hair Theorem, black holes are completely characterised by charge, mass, and angular momentum. Thus an antimatter star with the same amount of charge, same mass and same angular momentum with a matter star will, under ideal conditions, collapse into identical black hole. Therefore you don't have antimatter black hole. When colliding, these two black holes will thus, just merge.

 

[gendou2]

I would add that aside from mass, electric charge, and angular momentum, all information about the matter that falls into a black hole is lost.
So, it is meaningless to say that a black hole is either made either matter or antimatter.
There is no difference.

EDIT: I was beaten to the punch by yenchin.

 

[Herbascious J]

Interesting. So basically, it's the energy(or mass) that matters and that's all. Any Anti-matter anihilations would be hidden (if not out-right irrelevant). Thanks all.

 

[boredjavi]

well if it doesn't matter what kind of matter and energy go into a black hole what about hawking radiation where an anti matter particle will make the bh smaller

 

[bombadil]

...all information about the matter that falls into a black hole is lost..

No one knows if information is really lost when matter falls into a black hole. See http://en.wikipedia.org/wiki/Black_hole_information_paradox" ," by Susskind.