spacetoday.net: Two supermassive black holes found in same galaxy

Posted: Wed, Nov 20, 2002, 7:35 AM ET (1235 GMT)
Black holes in NGC 6240 (NASA/CXC/MPE/S.Komossa et al.)

Astronomers announced Tuesday that they have discovered for the first time two supermassive black holes in the same galaxy, objects that will likely collide in the distant future. Astronomers used images from the Chandra X-Ray Observatory to find that the galaxy NGC 6240, about 400 million light-years away, has two bright objects in its core. Previous observations at other wavelengths had detected two bright nuclei, but this was the first time the distinct nuclei were found in x-ray wavelengths, indicating that both were active black holes. The twin black holes may result from the recent merger of two smaller galaxies. The two black holes are expected to collide and merge over the next few hundred million years; the collision will generate gravitational waves that will spread across the universe.