http://arxiv.org/abs/1409.6309
The present constraints on neutrino masses led to the revision of their cosmological role, as the presence of a cosmological neutrino background is a clear prediction of the current standard cosmological models. In this paper, we extend the study of the impact of such background on the spatial distribution of both Dark Matter (DM) and galaxies in the Universe, by coupling N-body numerical simulations with semi-analytic models (SAMs) of galaxy formation. Starting from the same initial conditions, massive neutrino cosmologies predict a slower evolution of DM perturbations with respect to the corresponding LCDM cosmology and a suppression on the matter power spectrum on small and intermediate scales. The resulting statistical properties of model galaxies reflect the different growth of the Large Scale Structure, but we explicitly show that most of the deviations from a LCDM realisation are due to the different $\sigma_8$ associated with the massive neutrino cosmologies. We thus conclude that an independent estimate for the normalisation of the matter power spectrum is needed, in order to unambiguously characterise the effect of the neutrino background on the growth of structures in the Universe. We find that galaxy properties alone are a weak tracer of deviations from the LCDM realisation, but combining them with information about the overall matter distribution at all scales, it is possible to tailor test able to disentangle between the different cosmological models. Nonetheless, the deviations from a LCDM in runs with massive neutrinos go on opposite direction with respect to competing models like modified gravity, thus weakening any detectable cosmological signal. Given the ubiquitous presence of a neutrino background, this effect has to be taken in full account in the framework of future missions aimed at constraining the properties of the “Dark” components of the Universe.
F. Fontanot, F. Villaescusa-Navarro, D. Bianchi, et. al.
Wed, 24 Sep 14
59/62
Comments: MNRAS submitted; 8 pages, 4 figures, 1 table
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