Preprint typeset using LATEX style emulateapj v. 5/2/11 DIRECT NUMERICAL SIMULATION OF REIONIZATION II: RECOMBINATIONS, CLUMPING FACTORS, AND THE PHOTON BUDGET FOR REIONIZATION

We use a fully self-consistent cosmological simulation including dark matter dynamics, multi-species hydrodynamics, chemical ionization, flux limited diffusion radiation transport, and a param-eterized model of star formation and feedback (thermal and radiative) to investigate the epoch of hydrogen reionization in detail. Our numerical method is scalable with respect to the number of ra-diation sources, size of the mesh, and the number of computer processors employed, and is described in Paper I of this series. In this the first of several application papers, we investigate the mechanics of reionization from stellar sources forming in high-z galaxies, the utility of various formulations for the gas clumping factor on accurately estimating the effective recombination time in the IGM, and the photon budget required to achieve reionization. We also test the accuracy of the static and time-dependent models of Madau et al. as predictors of reionization completion/maintenance. We simulate a WMAP7 ΛCDM cosmological model in a 20 Mpc comoving cube, resolved with 8003 uniform fluid cells and dark matter particles. By tuning our star formation recipe to approx-imately match the observed high redshift star formation rate density and galaxy luminosity func-tion, we have created a fully coupled radiation hydrodynamical realization of hydrogen reionizatio