Local active black hole mass functions

Abstract

AbstractWhile black holes (BHs) are apparently a ubiquitous component of the nuclei of local spheroids, their role in galaxy evolution remains largely unknown. The tight correlations between galaxy spheroid properties and BH mass provide an important boundary condition for models of the coevolution of BHs and galaxies. Here we consider another important boundary condition: the local mass function of broad-line active galaxies. We use standard virial mass estimation techniques to examine the distribution of BH masses and accretion rates for active galaxies in the local universe, and we also compare the distribution of BH masses in local broad and narrow-line objects, and find that both populations have a characteristic mass of ∼107M⊙. Most importantly, this is the first BH mass function to consider BH with masses ∼106M⊙. The space density of this important population allows us to place constraints on potential mechanisms for the creation of seed BHs in the early Universe.