Big Apple Colloquium

Timothy Heckman (Johns Hopkins University)

The Co-Evolution of Galaxies and Black Holes: A Local Perspective

I will summarize recent investigations into the relation between the evolution of black holes and galaxies based on optical spectra and multi-color imaging of over 600,000 galaxies provided by the Sloan Digital Sky Survey. These data are complemented by radio data from the Very Large Array and vacuum ultraviolet images from the GALEX mission. I will show that the growth of supermassive black holes as traced by optically luminous active galactic nuclei is strongly linked to the on-going formation of stars in the bulge component of galaxies. It is likely that this co-evolution is driven by the accretion and radial transport of cold gas. Mergers of galaxies are only one way to drive this Flow. I will show that the characteristic mass scales for the populations of growing black holes and bulges are substantially lower now than in the past. The most massive black holes are largely quiescent today with low-level activity driven by the slow accretion of hot halo gas and/or gas shed by evolved stars. The weak radio jets such black holes produce nonetheless may play a key role in suppressing star formation, keeping their surrounding host galaxy "red and dead". Evidence for galaxy-scale feedback in the form of powerful AGN-driven outflows in the strongly accreting radio-quiet black holes is not clear. However, feedback from the massive stars whose formation seems to accompany the growth of the black hole can be significant in these objects.