What happens when black holes merge?

[Admin]

Black hole mergers are beautiful — and some of the most violent events in the cosmos. Here's how the process unfolds.

What happens when black holes merge? : Read more

 

[Unclear Engineer]

This article says:
"When black holes collide, they release more energy than every star in the universe — and all of it happens in complete, utter silence and darkness."

If they "release" that energy, I assume it goes out into the rest of the universe instead of being contained within the event horizon. So, how is it "utter silence and darkness"? Is it all gravitational waves, or is there some emission of light energy? What happens to the rest of the materials orbiting each of the black holes? Does it just smoothly go into orbit around the combined black hole, or does it emit energy from being disrupted?

Simulations are great, when you have equations that capture all of the effects. But, if you have incomplete equations, then simulations can produce misleading results. In particular, does General Relativity successfully describe how things work at the event horizon?

I have never heard of a black hole merger being viewed by an optical or radio telescope. Has it been attempted? What were the results?

 

[Hildy]

Out of curiosity, do any of the last parsec simulations include the possible influence of dark energy or dark matter?