Swift survey finds 'missing' active galaxies
Friday, January 21, 2011 - 16:31
in Astronomy & Space
Seen in X-rays, the entire sky is aglow. Even far away from bright sources, X-rays originating from beyond our galaxy provide a steady glow in every direction. Astronomers have long suspected that the chief contributors to this cosmic X-ray background were dust-swaddled black holes at the centers of active galaxies. The trouble was, too few of them were detected to do the job. An international team of scientists using data from NASA's Swift satellite confirms the existence of a largely unseen population of black-hole-powered galaxies.