An X-ray picture (false color) of the Abell 2104 cluster of galaxies taken with NASA's Chandra X-ray Observatory overlaid on an optical image taken with Carnegie Observatories' 6.5-meter Walter Baade telescope in Las Campanas, Chile. The Chandra image reveals X-ray emissions produced by both hot gas (the blue area near the center of the image) and by accretion of dust and gas onto supermassive black holes (the smaller blue patches on the outskirts of the image). The number of active, supermassive black holes found in this cluster is six times the amount found using other techniques.The finding suggests that active black holes are much more common in clusters of galaxies than previously believed. (Image courtesy NASA and the Carnegie Observatories.)