Using multi-wavelength infrared+optical+X-ray surveys, we measure the growth of supermassive black holes at the centers of galaxies over the last 12 billion years. Most actively growing black holes are heavily obscured and thus are not seen in optical surveys, like the Sloan Digital Sky Survey; at the same time, deep infrared and X-ray surveys like GOODS and COSMOS are too small to find rare objects like luminous SDSS quasars. So completing the census of black hole growth requires a new large-volume X-ray survey, "Stripe 82X," to explore obscured growth at high luminosity and/or high redshift. Theorists have suggested that mergers of gas-rich galaxies trigger Active Galactic Nuclei (AGN), whose radiation and/or outflows may quench star formation and strongly affect galaxy evolution ("feedback"). Our morphological analyses show that mergers probably do trigger luminous quasars but not the far more numerous moderate-luminosity AGN, which grow slowly through secular p rocesses. Indeed, for normal galaxies, we identify two distinct modes of galaxy evolution, with mergers and AGN feedback affecting only a minority. LIGO discoveries of gravitational waves from merging black holes potentially probe an interesting (low) mass range of black hole mergers.
Coffee: 3:30 pm, 245 Compton