Mergers, AGN, and Quenching Philip Hopkins 05/21/07 Lars Hernquist, TJ Cox, Dusan Keres, Volker Springel, Rachel Somerville (MPIA), Gordon Richards (JHU), Kevin Bundy (Caltech), Alison Coil (Arizona), Adam Lidz (CfA), Adam Myers (Illinois), Yuexing Li (CfA), Paul Martini (OSU), Ramesh Narayan (CfA), Elisabeth Krause (Bonn) Motivation QUASARS AND SPHEROID FORMATION Yang+ 03 Croton+ 06 Bell+ 04 Motivation CIRCUMSTANTIAL EVIDENCE Tremaine+ 02; Onken+ 04; Nelson+ 04; Peterson+ 04, 05; Barth+ 04, 05; Greene & Ho 05 Merloni+ 04 Motivation CIRCUMSTANTIAL EVIDENCE  Quasars were active/BHs formed when SF shut down... BH Formation Times: Spheroid Formation Times: Nelan+05; Thomas+05; Gallazzi+06 Hopkins, Lidz, Hernquist, Coil, et al. 2007 Motivation CIRCUMSTANTIAL EVIDENCE - = Borch+06; Bundy+06; Fontana+04,06; Pannella+06; Franceschini+06 Hopkins, Bundy, Hernquist+ 06 Motivation CIRCUMSTANTIAL EVIDENCE  Observed RS Buildup to z>~1 = Expectation if *all* new mass to the RS “transitions” in a quasar-producing merger Hopkins, Bundy, Hernquist+ 06 Motivation CIRCUMSTANTIAL EVIDENCE Sanchez+ ‘05 GEMS 0.5 < z < 1.1 Optical QSOs Nandra+ ‘06 DEEP2 (also, Kauffmann+ 03; 0.7 < z < 1.4 local SDSS hosts) X-ray QSOs Motivation CIRCUMSTANTIAL EVIDENCE “Transition”:  Move mass from Blue to Red: exhaust *all* cold gas  Rapid (<~ Gyr)  Small scales (~pc - kpc)  “Quasar” mode (high mdot): Soltan: most BH mass short-lived (~10^7-10^8 yr)  Morphological Transformation: violent relaxation Classical spheroid formation  Gas-rich/Dissipational Mergers Motivation WHAT DO WE KNOW? Mergers Hot Halos Secular classical bulges/ morphology: little effect “pseudobulges” spheroids little BH growth Seyferts? quasar & remnant BH/AGN: fuel for low small (<10^7 massive BH Mdot modes? M_sun) BHs kinematic accretion shocks Seyfert? feedback: quasar stellar winds starburst timescales: short (<Gyr) ~Hubble time ~Gyr?