Analytical models for the energetics of cosmic accretion shocks, their cosmological evolution, and the effect of environment

We present an analytical description of the energetics of the population of cosmic accretion shocks, for a con-cordance cosmology (Ω_m + Ω^Λ = 1). We calculate how the shock-processed accretion power and mass current are distributed among different shock Mach numbers and how they evolve with cosmic time. We calculate the cumulative energy input of cosmic accretion shocks of any Mach number to the intergalactic medium as a function of redshift and compare it with the energy output of supernova explosions, as well as with the energy input required to reionize the universe. In addition, we investigate and quantify the effect of environmental factors, such as local clustering properties and filament preheating, on the statistical properties of these shocks. We find that the energy processed by accretion shocks is higher than the supernova energy output for all z < 3 and that it becomes more than an order of magnitude higher in the local universe. The energy processed by accretion shocks alone becomes comparable to the energy required to reionize the universe by z ∼ 3.5. Finally, we establish both qualitatively and quantitatively that local clustering, as well as filament compression and preheating, are important factors in determining the statistical properties of the cosmic accretion shock population.