The Growth of Supermassive Black Holes Over Cosmic Time

Professor Meg Urry (hosted by Hynes), Yale Center for Astronomy & Astrophysics
March 8, 2017 at 4:00 pm
204 Crow
Event Description 

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