Cosmological Hydrogen Reionization with Three‐dimensional Radiative Transfer

We present new calculations of the inhomogeneous process of cosmological reionization by following the radiative transfer carefully in pre-computed hydrodynamical simulations of galaxy formation. These new computations represent an important step on the way towards fully self-consistent and adaptive calculations which will eventually cover the enormous range of scales from sizes of individual mini-halos to the mean free path of ionizing photons in the post-overlap Universe. The goal of such simulations is to include enough realistic physics to accurately model the formation of early structures and the end of the ‘dark ages’. Our new calculations demonstrate that the process by which the ionized regions percolate the Universe is complex, and that the idea of voids being ionized before overdense regions is too simplistic. It seems that observational information pertaining to the reionization epoch may now be in our grasp, through the detection of Gunn-Peterson troughs at z ∼ 6. If so, then the comparison of information from many lines of sight with simulations such as ours may allow us to disentangle details of the ionization history and trace the early formation of structure.