Keywords :
early universe; galaxies evolution; galaxies: formation; intergalactic medium; large-scale structure of universe; methods: numerical
Abstract:The ultraviolet background (UVB) emitted by quasars and galaxies governs the ionization and thermal state of the intergalactic medium (IGM), regulates the formation of high-redshift galaxies, and is thus a key quantity for modeling cosmic reionization. The vast majority of cosmological hydrodynamical simulations implement the UVB via a set of spatially uniform photoionization and photoheating rates derived from UVB synthesis models. We show that simulations using canonical UVB rates reionize and, perhaps more importantly, spuriously heat the IGM, much earlier (z~15) than they should. This problem arises because at z>6, where observational constraints are nonexistent, the UVB amplitude is far too high. We introduce a new methodology to remedy
...(more)
Abstract:
(hide)