Philip Hopkins

University of California, Berkeley

How do Massive Black Holes Get their Gas?

Super-massive black holes (SMBHs) and AGN are of fundamental interest both in their own right and to cosmology and galaxy formation. However, the physics of angular momentum transport from galactic scales to an accretion disk is one of the outstanding problems in our understanding of the formation and evolution of SMBHs. New, multi-scale hydrodynamic simulations can probe these scales and show for the first time that, when the proper physics is included, gravitational instabilities can drive inflow rates down to a viscous accretion disk sufficient to power the most luminous quasars. The last stage of this instability takes the form of a lopsided eccentric nuclear disk. Seemingly unrelated observations have discovered that there is a lopsided stellar disk of unknown origin orbiting the BH in M31, and possibly many other systems. I'll discuss how these nominally independent puzzles are in fact closely related -- the disk in M31 and other nearby galaxies may in fact be the 'smoking gun' for these instabilities and tell us how and when SMBHs were grown. The same disk dominates the AGN obscuration, and may be the putative torus invoked to explain obscured active galactic nuclei and the cosmic X-ray background. I'll discuss the implications of these simulations for BH fueling, quasar activity and obscuration, and the evolution of BH spin. Finally, I'll discuss what this means for models of AGN feedback and its effects on galaxy formation.