| Abstract: |
Observations of the Lya forest and of high-redshift galaxies at z ~ 6-10 imply that there were just enough photons to maintain the universe in an ionized state at z ~ 5-6, indicating a "photon starved" end to reionization. The ionizing emissivity must have been larger at earlier times in order to yield the extended reionization history implied by the electron scattering optical depth constraint from Wilkinson Microwave Anisotropy Probe (WMAP). I will address the possibility that a faint population of galaxies with host halo masses of ~1e8-1e9 Msun dominated the ionizing photon budget at redshifts z >~ 9, due to their much higher escape fractions. Such low-mass galaxies would not be present at later times due to photoionization heating in a reionized universe. I will then discuss the connection between this radiative feedback occurring at high redshift, and our local environment in the Milky Way. In particular I will describe large scale coupled realization of reionization and N-body simulations of structure formation in the local universe, and implications for the "missing satellites" problem. |
