Journal Article

Baryon history and cosmic star formation in non-Gaussian cosmological models: numerical simulations

Umberto Maio and Francesca Iannuzzi

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 415, issue 4, pages 3021-3032
Published in print August 2011 | ISSN: 0035-8711
Published online August 2011 | e-ISSN: 1365-2966 | DOI: http://dx.doi.org/10.1111/j.1365-2966.2011.18911.x
Baryon history and cosmic star formation in non-Gaussian cosmological models: numerical simulations

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We present the first numerical, N-body, hydrodynamical, chemical simulations of cosmic structure formation in the framework of non-Gaussian models. We study the impact of primordial non-Gaussianities on early chemistry (e, H, H+, H, He, He+, He++, H2, H+2, D, D+, HD, HeH+), molecular and atomic gas cooling, star formation, metal (C, O, Si, Fe, Mg, S) enrichment, Population III (popIII) and Population II–I (popII) transition and on the evolution of ‘visible’ objects.

We find that non-Gaussianities can have some consequences on baryonic structure formation at very early epochs, but the subsequent evolution at later times washes out any difference among the various models. When assuming reasonable values for primordial non-Gaussian perturbations, it turns out that they are responsible for (i) altering early molecular fractions in the cold, dense gas phase by ∼10 per cent; (ii) inducing small temperature fluctuations of ≲10 per cent during the cosmic evolution of primordial objects; (iii) influencing the onset of the first star formation events, at z > 15, and of the popIII/popII transition by up to some 107 yr; (iv) determining variations of ≲10 per cent in the gas cloud and stellar mass distributions after the formation of the first structures; and (v) causing only mild variations in the chemical history of the Universe. We stress, though, that purely non-Gaussian effects might be difficult to address, since they are strictly intertwined with additional physical phenomena (e.g. primordial gas bulk flows, unknown primordial popIII stellar mass function etc.) that have a similar or stronger impact on the behaviour of the baryons.

Keywords: cosmology: theory; dark ages, reionization, first stars; dark matter; large-scale structure of Universe

Journal Article.  8853 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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