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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, c2eff. 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, Issue 8, Page 083501_1
2012 April

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Instituto de Astrofísica e Ciências do Espaço Universidade do Porto Faculdade de Ciências da Universidade de Lisboa
Fundação para a Ciência e a Tecnologia COMPETE 2020 PORTUGAL 2020 União Europeia