We present the first large-scale radiative transfer simulations of cosmicreionization, in a simulation volume of (100/h Mpc)^3, while at the same timecapturing the dwarf galaxies which are primarily responsible for reionization.We achieve this by combining the results from extremely large, cosmological,N-body simulations with a new, fast and efficient code for 3D radiativetransfer, C^2-Ray. The resulting electron-scattering optical depth is in goodagreement with the first-year WMAP polarization data. We show that reionizationclearly proceeded in an inside-out fashion, with the high-density regions beingionized earlier, on average, than the voids. Ionization histories ofsmaller-size (5 to 10 comoving Mpc) subregions exibit a large scatter about themean and do not describe the global reionization history well. The minimumreliable volume size for such predictions is ~30 Mpc. We derive thepower-spectra of the neutral, ionized and total gas density fields and showthat there is a significant boost of the density fluctuations in both theneutral and the ionized components relative to the total at arcminute andlarger scales. We find two populations of HII regions according to their size,numerous, mid-sized (~10 Mpc) regions and a few, rare, very large regions tensof Mpc in size. We derive the statistical distributions of the ionized fractionand ionized gas density at various scales and for the first time show that bothdistributions are clearly non-Gaussian. (abridged)
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