Open AccessCosmic reionization constraints on the nature of cosmological perturbations
Author(s) -
Avelino Pedro P.,
Liddle Andrew R.
Publication year - 2006
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1111/j.1365-2966.2006.10815.x
Subject(s) - reionization , physics , cmb cold spot , astrophysics , redshift , dark ages , optical depth , cosmic cancer database , gaussian , cosmic microwave background , universe , quasar , cosmic variance , galaxy , quantum mechanics , aerosol , anisotropy , meteorology
ABSTRACT We study the reionization history of the Universe in cosmological models with non‐Gaussian density fluctuations, taking them to have a renormalized χ 2 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.