Spherical "Top-Hat" collapse in a modified Chaplygin gas dominated universe

Abstract

Considering perturbation growth in spherical Top-Hat (STH) model of structure formation in a generalized Chaplygin gas (GCG) dominated universe, we want to study this scenario with modified Chaplygin gas (MCG) obeying an equation of state p = A−B/ρ α model. Different parameters of this scenario for positive and negative values of A are computed. The evolution of background and collapsed region parameters are found for different cases. The stability of the model and the collapse time rate are considered in different cases. The turn-around redshifts for different values of α are computed; the results are in relatively good agreement with current observational data. PACS Number(s): 98.80. 98.80.Es, 95.35.+d, 95.36.+x † Corresponding author. 1550050-1 Int. J. Mod. Phys. D 2015.24. Downloaded from www.worldscientific.com by CAMBRIDGE UNIVERSITY on 08/16/15. For personal use only.

Viscous Chaplygin gas models as spherical top-hat collapsing fluids

“…Also, the perturbed EoS remains positive at the present epoch as well as near future ( Figures 5 and 11) in both cases. It can be also remarked that some of our results are consistence with [9,10,14,19,20,21].…”

“…Hence, by following the procedure of [20,21], we can get density contrast and divergence of peculiar velocity for VMVCG in the following for Einstein gravity…”

“…Recently, Karbasi and Razmi [20] have discussed the STHC in the presence of MCG. Also, Ujjal and Mubasher [21] have analyzed the STHC sce-nario in the presence of viscus MCG in Einstein and loop quantum gravities.…”

Viscous Chaplygin Gas Models as a Spherical Top-Hat Collapsing Fluids

“…The basic equations about the density contrast and divergence of peculiar velocity in perturbed region are presented in the Appendix. Hence, by following the procedure of [20,21], we can get density contrast and divergence of peculiar velocity for VMVCG in the following for Einstein gravity…”

“…Recently, Karbasi and Razmi [20] have discussed the STHC in the presence of MCG. Also, Ujjal and Mubasher [21] have analyzed the STHC sce-nario in the presence of viscus MCG in Einstein and loop quantum gravities.…”