Cosmic reionization constraints on the nature of cosmological perturbations


We study the reionization history of the Universe in cosmological models with non-Gaussian density fluctuations, taking them to have a renormalized χ probability distribution function parametrized by the number of degrees of freedom, ν. We compute the ionization history using a simple semi-analytical model, considering various possibilities for the astrophysics of reionization. In all our models we require that reionization is completed prior to z= 6, as required by the measurement of the Gunn–Peterson optical depth from the spectra of high-redshift quasars. We confirm previous results demonstrating that such a non-Gaussian distribution leads to a slower reionization as compared to the Gaussian case. We further show that the recent WMAP three-year measurement of the optical depth due to electron scattering, τ = 0.09± 0.03, weakly constrains the allowed deviations from Gaussianity on the small scales relevant to reionization if a constant spectral index is assumed. We also confirm the need for a significant suppression of star formation in minihaloes, which increases dramatically as we decrease ν.

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@inproceedings{Avelino2006CosmicRC, title={Cosmic reionization constraints on the nature of cosmological perturbations}, author={Pedro Avelino and Andrew R. Liddle}, year={2006} }