Supermassive black holes reaching millions of solar masses have been detected at the centers of active galaxies, and their formation has been associated with mergers of stars or very active star formation regions, such as starburst regions.
Matsushita et al. imaged the distribution of molecular gas in the irregular galaxy Messier 82 (M82) using the Nobeyama Millimeter Array (NMA) in order to understand its dynamical nature and how it may relate to the formation of a supermassive black hole, known as a superbubble. The superbubble is offset from the center of M82 in a starburst region, which also contains a hard X-ray variable point source that is probably due to a massive black hole of about 460 solar masses. The spatial relations between the starburst region, the superbubble, and the massive black hole support a related origin. The authors suggest that about 1000 supernovae exploded in the starburst region to form the superbubble and the massive black hole. This massive black hole, which is offset from the center of M82, may eventually gravitate toward the center and merge with the supermassive black hole. Thus, less massive black holes could form in starburst regions offset from the center of an active galaxy and then drift toward the center to form, or build upon, the central supermassive black hole. — LR
Astrophys. J., in press, astroph0011071.