A Cosmological Framework for the Co-Evolution of Quasars, Supermassive Black Holes, and Elliptical Galaxies: I. Galaxy Mergers & Quasar Activity

Understand

(Abridged) We develop a model for the cosmological role of mergers in the evolution of starbursts, quasars, and spheroidal galaxies.

• Combining halo mass functions (MFs) with empirical halo occupation models, we calculate where major galaxy-galaxy mergers occur and what kinds of galaxies merge, at all redshifts.
• We compare with observed merger MFs, clustering, fractions, and small-scale environments, and show that this yields robust estimates in good agreement with observations.
• Making the simple ansatz that major, gas-rich mergers cause quasar activity, we demonstrate that this naturally reproduces the observed rise and fall of the quasar luminosity density from z=0-6, as well as quasar LFs, fractions, host galaxy colors, and clustering as a function of redshift and luminosity.