Two astronomers have spotted a black hole pair and on a collision course with each other. BAM!
Tomorrow in Nature, the two researchers report finding telltale twin hydrogen lines in the quasar's spectrum, instead of the one line that would emanate from a single black hole. Based on the twin lines, Boroson and Lauer calculate that two supermassives are separated by only 0.3 light-years--one-tenth the distance from the sun to its nearest neighbor--and are orbiting each other at the blinding speed of 6000 kilometers per second. For comparison, the sun's orbital speed around the galaxy's center is about 220 kilometers per second. "Sometimes discoveries depend on recognizing something as interesting even if it wasn't what you were looking for," Boroson says. If this one is confirmed, he adds, it should vastly improve what astronomers know about how supermassives merge and how they light up quasars.
The paper has been published in Nature, including a News and Views article on it.
 T.A. Boroson and T.R. Lauer, Nature v.458, p.53 (2009).
 J.M. Miller, Nature v.458, p.40 (2009).