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We measure several properties of the reionization process and thecorresponding low-frequency 21-cm signal associated with the neutral hydrogendistribution, using a large volume, high resolution simulation of cosmicreionization. The brightness temperature of the 21-cm signal is derived bypost-processing this numerical simulation with a semi-analytical prescription.Our study extends to high redshifts (z ~ 25) where, in addition to collisionalcoupling, our post-processed simulations take into account the inhomogeneitiesin the heating of the neutral gas by X-rays and the effect of an inhomogeneousLya radiation field. Unlike the well-studied case where spin temperature isassumed to be significantly greater than the temperature of the cosmicmicrowave background due to uniform heating of the gas by X-rays, spatialfluctuations in both the Lya radiation field and X-ray intensity impactpredictions related to the brightness temperature at z > 10, during the earlystages of reionization and gas heating. The statistics of the 21-cm signal fromour simulation are then compared to existing analytical models in theliterature and we find that these analytical models provide a reasonablyaccurate description of the 21-cm power spectrum at z < 10. Such an agreementis useful since analytical models are better suited to quickly explore the fullastrophysical and cosmological parameter space relevant for future 21-cmsurveys. We find, nevertheless, non-negligible differences that can beattributed to differences in the inhomogeneous X-ray heating and Lya couplingat z > 10 and, with upcoming interferometric data, these differences in returncan provide a way to better understand the astrophysical processes duringreionization.

Cosmic Reionization and the 21-cm signal: Comparison between an analytical model and a simulation