Spherical collapse in Generalized Dark Matter models

Abstract

The influence of considering a generalized dark matter (GDM) model, which allows for a non-pressure-less dark matter and a non-vanishing sound speed in the non-linear spherical collapse model is discussed for the Einstein-de Sitter-like (EdSGDM) and $\Lambda$GDM models. By assuming that the vacuum component responsible for the accelerated expansion of the Universe is not clustering and therefore behaving similarly to the cosmological constant $\Lambda$, we show how the change in the GDM characteristic parameters affects the linear density threshold for collapse of the non-relativistic component (${\delta }_{\mathrm{c}}$) and its virial overdensity (${\Delta }_{\mathrm{V}}$). We found that the generalized dark matter equation of state parameter $w_{\mathrm{gdm}}$ is responsible for lower values of the linear overdensity parameter as compared to the standard spherical collapse model and that this effect is much stronger than the one induced by a change in the generalized dark matter sound speed $c_{\mathrm{s},\mathrm{gdm}}^2$. We also found that the virial overdensity is only slightly affected and mostly sensitive to the generalized dark matter equation of state parameter $w_{\mathrm{gdm}}$. These effects could be relatively enhanced for lower values of the matter density. Finally, we found that the effects of the additional physics on ${\delta }_{\mathrm{c}}$ and ${\Delta }_{\mathrm{V}}$, when translated to non-linear observables such as the halo mass function, induce an overall deviation of about 40\% with respect to the standard $\Lambda$CDM model at late times for high mass objects. However, within the current linear constraints for $c_{\mathrm{s},\mathrm{gdm}}^2$ and $w_{\mathrm{gdm}}$, we found that these changes are the consequence of properly taking into account the correct linear matter power spectrum for the GDM model while the effects coming from modifications in the spherical collapse model remain negligible.

Published in Physical Review D - no major corrections to the first version - new sections added

References in corpus (8)

• Dark Energy and the Accelerating Universe
• The DESI Experiment Part I: Science,Targeting, and Survey Design
• KiDS-450: The tomographic weak lensing power spectrum and constraints on cosmological parameters
• Structure formation in the presence of dark energy perturbations
• On the implementation of the spherical collapse model for dark energy models
• WFIRST: The Essential Cosmology Space Observatory for the Coming Decade
• Constraints on shear and rotation with massive galaxy clusters
• Cluster counts. II. Tensions, massive neutrinos, and modified gravity

Cited by in corpus (7)

• The halo model for cosmology: a pedagogical review
• Testing generalized logotropic models with cosmic growth
• Constraints on dark matter self-interaction from galactic core size
• Spherical Collapse Approach for Non-standard Dark Matter Models and Enhanced Early Galaxy Formation in JWST
• Effects of non-vanishing dark matter pressure in the Milky Way galaxy
• Spherical collapse in DGP braneworld cosmology
• Compact Groups in GDM Cosmological Simulations