The two bright sources at the center of this composite x-ray (blue) and radio (pink) image are co-orbiting supermassive black holes powering the giant radio source 3C 75. They about 25,000 light-years apart and surrounded by super hot (> 1,000,000°) x-ray emitting gas while they blast out jets of relativistic particles. The black holes are at the cores of two merging galaxies in a galaxy cluster they are some 300 million light-years away. They appear to be bound together by gravity in a binary system as evidenced by their jets’ consistent swept back appearance which is probably caused by their common motion as through the hot cluster gas at 1200 km/s. Such cosmic mergers are thought to be common in crowded galaxy cluster environments in the distant universe. The mergers are expected to be intense sources of gravitational waves in their final stages.

Image Credit: NASA / NRAO