Determining the Properties and Evolution of Red Galaxies from the Quasar Luminosity Function

Abstract

We study the link between quasars and the red galaxy population using a model for self-regulated growth of supermassive black holes in gas-rich galaxy mergers. Using a model for quasar evolution motivated by hydrodynamic merger simulations, we deconvolve the observed quasar luminosity function at various redshifts to determine the rate of formation of black holes of a given final mass. Identifying quasar activity with the formation of spheroids in the framework of the merger hypothesis, this implies a corresponding rate of formation of spheroids with given properties as a function of redshift. This allows us to predict, for the red galaxy population, the distribution of galaxy velocity dispersions; mass functions; star formation rates; luminosity functions in many observed wave bands (NUV, U , B , V , R , I , J , H , K ); the total red galaxy number, mass, and luminosity densities; color distributions as a function of magnitude and velocity dispersion for several different wave bands; the distribution of mass-to-light ratios versus mass; luminosity-size relations; and the typical ages and distribution of ages (formation redshifts) as a function of mass and luminosity. For each of these quantities, we predict the evolution from redshift z = 0-6. Each of our predictions agrees well with existing observations, without the addition of tunable parameters; the essential observational inputs come from the observed quasar luminosity function. These predictions are skewed by several orders of magnitude if we adopt simpler, traditional models of quasar lifetimes instead of the more complicated evolution implied by our simulations.