Cosmic reionization constraints on the nature of cosmological perturbations

Abstract

We study the reionization history of the Universe in cosmological models with non-Gaussian density fluctuations, taking them to have a renormalized ${\chi }^2$ probability distribution function parametrized by the number of degrees of freedom, $\nu$. 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, $\tau =0.09\pm 0.03$, 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 mini-halos, which increases dramatically as we decrease $\nu$.

arXiv comment5 pages, 5 figures

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Cited by in corpus (3)

• Evolution of Massive Haloes in non-Gaussian Scenarios
• Primordial non-Gaussianity in the large scale structure of the Universe
• The effects of primordial non-Gaussianity on the cosmological reionization