Astronomers Discover 33 Pairs of Waltzing Black Holes

Astronomers from UC Berkeley have identified 33 pairs of waltzing black holes, closing the gap somewhat between the observed population of super-massive black hole pairs and what had been predicted by theory. "Astronomical observations have shown that 1) nearly every galaxy has a central super-massive black hole (with a mass of a million to a billion times the mass of the Sun), and 2) galaxies commonly collide and merge to form new, more massive galaxies. As a consequence of these two observations, a merger between two galaxies should bring two super-massive black holes to the new, more massive galaxy formed from the merger. The two black holes gradually in-spiral toward the center of this galaxy, engaging in a gravitational tug-of-war with the surrounding stars. The result is a black hole dance, choreographed by Newton himself. Such a dance is expected to occur in our own Milky Way Galaxy in about 3 billion years, when it collides with the Andromeda Galaxy."

Re:Good news for gravitational waves hunters

[bcrowell]

The same thing occurred to me. Here [arxiv.org] is what appears to be the paper describing the observations. It's remarkably silent on whether any of this has implications for gravitational wave astronomy or tests of general relativity. They basically seem to see it as purely a way of finding out about evolution of galaxies. I guess the fact that these pairs are reasonably frequent implies that you can make reasonable estimates, probably for the first time, of the rate at which black hole collisions should be expected. I wonder to what extent these black hole pairs can be used as laboratories for testing general relativity in the same sense as the Hulse-Taylor pulsar [wikipedia.org], even before they merge. I guess the orbital periods would be very long, though.

Re:Wow!

[gstoddart]

Was this a creationist university?

*laugh* No, but it was pre-Hubble before they'd actually done the measurements to be fairly sure. There was strong theoretical evidence, but nothing they'd been able to hold up until '94 when they looked at M87. (Yes, there had been some evidence, but not yet conclusive.)

Some of us went to university a long time ago, and the world has changed a lot since then.

Like I said, I just continue to be amazed at the changes in my lifetime. You young kids think we've always known this stuff. :-P

begging your pardon sir, but it's a big-ass sky

;-)

Cheers