Evolution of the Ionizing Radiation Background and Star Formation in the Aftermath of Cosmological Reionization

Abstract

The temporal evolution of the ionizing UV background radiation field athigh redshift provides a probe of the evolution of the early starformation rate. By comparing the observed levels of absorption in thehighest redshift quasar spectra to the predictions of a hydrodynamicsimulation, we determine the evolution of the photoionization rate(Γ) for neutral hydrogen in the intergalactic medium over theredshift range 4.9