1110.0491 (Umberto Maio)

Gas distribution, metal enrichment, and baryon fraction in Gaussian and non-Gaussian universes    [PDF]

Umberto Maio

We study the cosmological evolution of baryons in universes with and without primordial non-Gaussianities via (large scale) N-body/hydrodynamical simulations, including gas cooling, star formation, stellar evolution, chemical enrichment from both population III and population II regimes, and feedback effects. We find that large fnl values for non-Gaussianities can alter the gas probability distribution functions, the metal pollution history, the halo baryon, gas and stellar fractions, mostly at early times. More precisely: (i) non-Gaussianities lead to an earlier evolution of primordial gas, structures, and star formation; (ii) metal enrichment starts earlier (with respect to the Gaussian scenario) in non-Gaussian models with larger fnl; (iii) gas fractions within the haloes are not significantly affected by the different values of fnl, with deviations of ~1-10%; (iv) the stellar fraction is quite sensitive to non-Gaussianities at early times, with discrepancies reaching up to a factor of ~10 at very high z, and rapidly converging at low z; (v) the trends at low redshift are independent from fnl: they are mostly led by the ongoing baryonic evolution and by the feedback mechanisms, which determine a ~25%-30% discrepancy in the baryon fraction of galaxy groups/clusters with respect to the cosmic values; (vi) non-Gaussianity impacts on the cluster X-ray emission or on the SZ effect(s) are expected to be not very large and dominated by feedback mechanisms, whereas some effects on the 21-cm emission can be expected at early times; (vii) in order to address non-Gaussianities in the cosmological structure contest, high-redshift (z~10) investigations are required: first stars, galaxies, quasars, and GRBs may be potential cosmological probes of non-Gaussianities.

View original: http://arxiv.org/abs/1110.0491