Large‐Scale Simulations of Reionization

We use cosmological simulations to explore the large-scale effects ofreionization. Since reionization is a process that involves a large dynamicrange - from galaxies to rare bright quasars - we need to be able to cover asignificant volume of the universe in our simulation without losing hteimportant small scale effects from galaxies. Here we have taken an approachthat uses clumping factors derived from small scale simulations to approximatethe radiative transfer on the sub-cell scales. Using this technique, we cancover a simulation size up to $1280 h^{-1} Mpc$ with $10 h^{-1} Mpc$ cells.This allows us to construct synthetic spectra of quasars similar to observedspectra of SDSS quasars at high reshifts and compare them to the observationaldata. These spectra can then be analyzed for HII region sizes, the presence ofthe Gunn-Peterson trough and the Lyman-$\alpha$ forest.Comment: 25 page