Institute of Astronomy

Supermassive Black Hole Growth and Galaxy Evolution

SpeakerTalk DateTalk Series
Meg Urry (Yale University)15 March 2016Institute of Astronomy Colloquia


Using multi-wavelength surveys like GOODS, COSMOS, and Stripe 82X, we measure the growth of supermassive black holes at the centers of galaxies over the last approx 12 billion years. Most actively growing black holes are heavily obscured and thus are not seen in large optical surveys, like the Sloan Digital Sky Survey; at the same time, the deep multi-wavelength
surveys are too small to find rare objects like luminous SDSS quasars. So completing the census of black hole growth will require a large-volume
X-ray survey, to explore obscured growth at high luminosity and/or high redshift. Theorists have suggested that mergers trigger Active Galactic
Nuclei (AGN), whose radiation and/or outflows may quench star formation and strongly affect galaxy evolution (³feedback²). But our morphological
analyses showed that most moderate luminosity AGN at redshifts z ~1-2 have not undergone a recent major merger. Finally, using morphological
classifications in the local universe from Galaxy Zoo, we identify two distinct modes of galaxy evolution in the local universe, with mergers and
AGN feedback affecting only a minority.


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