Random Walk
Cosmic Collisions
Newly discovered black-hole pairs provide a rare glimpse into the later stages of how their host galaxies collide and merge. The images on the left, from the Sloan Digital Sky Survey, each show a single blurry object. Now the Keck telescope’s adaptive optics have resolved each smudge into two active galactic nuclei (right), each of which is powered by a supermassive black hole. These binary black holes are a hundred to a thousand times closer to each other than most previously observed pairs—and these 16 pairs are the largest population of such objects discovered with a systematic search. Postdoc Hai Fu, Professor of Astronomy George Djorgovski, Member of the Professional Staff Lin Yan (PhD ’96), and Alan Stockton of the University of Hawaii at Manoa, reported their observations at the American Astronomical Society meeting in January.
