Viewed in visible light, Markarian 739 resembles a smiling face, with a pair of bright cores underscored by an arcing spiral arm. The object is really a pair of merging galaxies. Data from Swift and Chandra reveal the western core (right) to be a previously unknown AGN; past studies already had identified an AGN in the eastern core. The two supermassive black holes are separated by about 11,000 light-years. The galaxy is 425 million light-years…
