07 March 2009
From: National Optical Astronomy Observatory
"Finding a needle in a haystack might be easy compared to finding two very similar black holes closely orbiting each other in a distant galaxy.
Astronomers from the National Optical Astronomy Observatory (NOAO) in Tucson have found what looks like two massive black holes orbiting each other in the center of one galaxy. It has been postulated that twin black holes might exist, but it took an innovative, systematic search to find such a rare pair.
The newly identified black holes appear to be separated by only 1/10 of a parsec—a tenth of the distance from Earth to the nearest star. This discovery of the most plausible binary black hole candidate ever found may lead to a greater understanding of how massive black holes form and evolve at the center of galaxies. Their results are published in this week’s edition of the journal Nature.
After a galaxy forms it is likely that a massive black hole can also form at its center. Since many galaxies are found in cluster of galaxies, individual galaxies can collide with each other as they orbit in the cluster. The mystery is what happens to these central black holes when galaxies collide and ultimately merge together. Theory predicts that they will orbit each other and eventually merge into an even larger black hole.
Each black hole is surrounded by a disk of material gradually spiraling into its grasp, releasing radiation from x-rays to radio waves. The two black holes complete an orbit around their center of mass every 100 years, traveling with a relative velocity of 6000 kilometers per second.
Credit: p. Marenfeld and NOAO/AURA/NSF" - Check out the rest of the article with the link above.
From Denny: As someone who does a lot of needle in a haystack kind of research I can really appreciate these guys' efforts! More than that let's celebrate their find, wow! the statistical probability of ever finding this unusual phenomenon...