Quasars and their enviroments along cosmic history

The observed properties of supermassive black holes suggest a fundamental link between their assembly and the formation of their host spheroids. We model the growth and activity of black holes in galaxies using ΛCDM cosmological hydrodynamic simulations. We study the evolution of the metal enrichment in quasar hosts and hence explore the relationship between star/spheroid formation and black hole growth/activity in galaxies. Using the simulations we approach the epoch of the first quasars and the first significant star formation activity. We show that the hosts of the rare bright quasars at z∼5-6 have star formation rates of several hundred M_⊙ yr^-1, and halo masses of order ∼1012 M_⊙. Already at these redshifts they have supersolar (Z/Z_⊙ ∼ 2-3) central metallicities, with a mild dependence of metallicity on luminosity, consistent with observed trends.