department of astronomy - courses  
home dept of astronomy mcdonald observatory research hobby-eberly telescope directory university of texas  
department of astronomy
mcdonald observatory
hobby-eberly telescope
university of texas
AST 386S





Phil Hopkins
Harvard University

Black Hole Feedback: Uniting Mergers, Quasars, and Red Galaxy Formation

Observations are increasingly probing each aspect of the evolutionary model for starbursts, quasars, and spheroidal galaxies, in which mergers between gas-rich galaxies drive nuclear inflows of gas, producing intense starbursts and feeding buried growth of supermassive black holes until feedback expels gas and renders a briefly visible optical quasar. These observations imply with increasing emphasis that black hole feedback must play a critical role. Using a large suite of hydrodynamical simulations of galaxy mergers we quantify the relation between the different stages of this evolutionary sequence. Quasar light curves and accretion rate evolution are qualitatively different when feedback couples to the surrounding ISM, and the quasar lifetime and column density distribution can be understood as a function of both instantaneous and peak quasar luminosity in this regime. We determine these dependencies and use them to de-convolve the observed quasar luminosity function to determine the formation and evolution of quasars and to map this distribution to others in the evolutionary sequence. With this formalism, we can predict a wide variety of black hole properties, the X-ray background spectrum, red galaxy distributions, and ongoing merger starburst fractions and distributions at redshifts z=0-6, and the structure and signatures of feedback-driven outflows. Essentially, the bright quasar population can directly inform our theoretical and observational picture of the buildup of much more difficult to observe merger, red galaxy, and ULIRG populations. Black hole feedback is a vital link in these distributions, and with (but not without) it, these distributions are all self-consistent and their statistics follow from their being manifestations of the same fundamental evolutionary process.


9 March 2006
Astronomy Program · The University of Texas at Austin · Austin, Texas 78712
prospective student inquiries:
site comments: