Spherical “Top-Hat” Collapse in general-Chaplygin-gas-dominated universes

R. A. A. Fernandes, J. P. M. de Carvalho, A. Yu. Kamenchtchik, U. Moschella, A. C. da Silva

Abstract
We expand previous works on the spherical ‘top-hat’ collapse (SC-TH) framework in generalized Chaplygin gas (gCg) dominated universes. Here we allow the collapse in all energetic components within the system. We analyze the non-linear stages of collapse for various choices of parameter α of the gCg model introducing an exact formulation for the so-called effective sound speed, c²_eff. We show that, within the SC-TH framework, the growth of the structure becomes faster with increasing values of α. This partially contradicts previous results obtained using an approximation in the context of linear perturbation theory.

Physical Review D
Volume 85, Page 083501_1
April 2012

DOI: 10.1103/PhysRevD.85.083501
ADS Bibliographic code: 2012PhRvD..85h3501F