The Epoch of Reionization in Warm Dark Matter Scenarios

Abstract

In this paper we investigate how the Reionization process is affected by early galaxy formation in different cosmological scenarios. We use a semi-analytic model with suppressed initial power spectra to obtain the UV Luminosity Function in thermal Warm Dark Matter and sterile neutrino cosmologies. We retrace the ionization history of intergalactic medium with hot stellar emission only, exploiting fixed and mass-dependent photons escape fraction (fesc). For each cosmology, we find an upper limit to fixed fesc, which guarantees the completion of the process at z<6.7. The analysis is tested with two limit hypothesis on high-z ionized hydrogen volume fraction, comparing our predictions with observational results. We then implement a blast-wave model, which explains the genesis of UV photons escape fraction in the context of feedback and co-evolution between galaxies and Active Galactic Nuclei. Including the AGNs contribution, we find that the neutral hydrogen ionization is almost complete at z<7, with a weak dependence on initial gaseous ionized fraction and accretion UV spectral slope.