Journal Article

Spherical collapse model with shear and angular momentum in dark energy cosmologies

A. Del Popolo, F. Pace and J. A. S. Lima

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 430, issue 1, pages 628-637
Published in print March 2013 | ISSN: 0035-8711
Published online January 2013 | e-ISSN: 1365-2966 | DOI: https://dx.doi.org/10.1093/mnras/sts669
Spherical collapse model with shear and angular momentum in dark energy cosmologies

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We study, for the first time, how shear and angular momentum modify typical parameters of the spherical collapse model, in dark-energy-dominated universes. In particular, we study the linear density threshold for collapse δc and the virial overdensity ΔV for several dark energy models and its influence on the cumulative mass function. The equations of the spherical collapse are those obtained in Pace et al., who used the fully non-linear differential equation for the evolution of the density contrast derived from Newtonian hydrodynamics, and assumed that dark energy is present only at the background level. With the introduction of the shear and rotation terms, the parameters of the spherical collapse model are now mass dependant. The results of the paper show, as expected, that the new terms considered in the spherical collapse model oppose the collapse of perturbations on galactic scale giving rise to higher values of the linear overdensity parameter with respect to the non-rotating case. We find a similar effect also for the virial overdensity parameter. For what concerns the mass function, we find that its high-mass tail is suppressed, while the low-mass tail is slightly affected except in some cases, e.g. the Chaplygin gas case.

Keywords: methods: analytical; cosmology: theory; dark energy

Journal Article.  6591 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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