The formation of ellipticals, black holes and active galactic nuclei: a theoretical perspective

In models of galaxy formation in a hierarchically clustering universe, elli pticals and bulges form through the merging of smaller disc galaxies. We di scuss when and where ellipticals form and how their observed properties are expected to vary as a function of mass, environment and redshift. We also present a model in which supermassive black holes are formed and quasars ar e fuelled during the same major mergers that produce the ellipticals. We sh ow that me can reproduce quantitatively the observed relation between bulge luminosity and black-hole mass, the strong evolution of the quasar populat ion with redshift, and the relation between the luminosities of nearby quas ars and those of their host galaxies.