Two Black Holes Dancing in 3C 75

What's happening at the center of active galaxy 3C 75? The two bright sources at the center
of this composite x-ray (blue)/ radio (pink) image are co-orbiting supermassive black holes
powering the giant radio source 3C 75. Surrounded by multimillion degree x-ray emitting
gas, and blasting out jets of relativistic particles the supermassive black holes are separated
by 25,000 light-years. At the cores of two merging galaxies in the Abell 400 galaxy cluster
they are some 300 million light-years away. Astronomers conclude that these two supermassive
black holes are bound together by gravity in a binary system in part because the jets' consistent
swept back appearance is most likely due to their common motion as they speed through the
hot cluster gas at 1200 kilometers per second. Such spectacular cosmic mergers are thought to
be common in crowded galaxy cluster environments in the distant universe. In their final stages
the mergers are expected to be intense sources of gravitational waves. >