spacetoday.net: Binary black hole system discovered

Posted: Fri, Mar 6, 2009, 6:34 AM ET (1134 GMT)
Dual supermassive black holes illus. (NOAO)

Astronomers have found for the first time a pair of supermassive black holes orbiting each other, the result of a previous collision of galaxies. NOAO astronomers discovered the binary black hole system by detecting the distinctive dual emission line signature in the center of one of 17,500 quasars discovered by the Sloan Digital Sky Survey. The two black holes have masses of 20 million and nearly one billion solar masses, and orbit each other at a distance of about a third of a light year. While many galaxies have supermassive black holes at the cores, this first-of-a-kind dual black hole system is likely the result of a previous collision between two galaxies. The two black holes will eventually merge with each other.