The infrared universe: The cosmic evolution of superstarbursts and massive black holes

Abstract

Abstract. Our view of galaxy evolution has been dramatically enhanced by recent deep field surveys at far-infrared and submillimeter wavelengths. Current evidence suggests that the number density of the most luminous far-infrared sources evolves strongly with redshift, and that the luminosity density in the far-infrared/submillimeter may exceed that in the optical/ultraviolet by factors of 3 − 10 at redshifts z > 1. If true, then as much as 80-90% of the "activity" in galaxies at z > 1 may be hidden by dust. Surveys of complete samples of luminous infrared galaxies in the local Universe show that the majority, if not all objects with log (L ir/L ) > ∼ 11.6, appear to be major mergers of molecular gas-rich disks accompanied by dust-enshrouded nuclear starbursts and powerful AGN. If the majority of the deep-field sources are simply more distant analogs of local luminous infrared galaxies, then we may be witnessing at z ∼ 1 − 3 the primary epoch in the formation of spheroids and massive black holes. This major event in galaxy evolution is largely missed by current deep optical/ultraviolet surveys.