The co-evolution of black holes, almost unfathomable in their bulk, and the even more massive galaxies that host them remains poorly understood—a kind of chicken-and-egg problem on mammoth scales. Do black holes, such as the lunker in our own Milky Way Galaxy, which contains the mass of four million suns (that’s about eight undecillion, or 8 x 10^36 kilograms), drive the evolution of galaxies around them; or do galaxies naturally nurture the gravitational gobblers at their centers; or perhaps do they come into being together, as a matched pair?
A serendipitous discovery in a relatively close-by dwarf galaxy may help answer that question. Amy Reines, a graduate student in astronomy at the University of Virginia (U.V.A.), was looking at bursts of star formation in a galaxy known as Henize 2-10, which serves as a kind of observational proxy for galaxies that existed in the early universe. She noticed a suspicious radio wave source coming from a small region of the galaxy, a good distance removed from the active stellar nurseries. A comparison with archival data showed x-ray radiation from the same location within Henize 2-10; the balance of radiation levels in different wavelengths pointed to the presence of a giant black hole accreting material from its surroundings.