EAS Publications Series

Issue		EAS Publications Series Volume 36, 2009 Dark Energy and Dark Matter: Observations, Experiments and Theories
Page(s)		17 - 24
DOI		10.1051/eas/0936003
Published online		30 May 2009

Dark Energy and Dark Matter: Observations, Experiments and Theories
E. Pécontal, T. Buchert, Ph. Di Stefano and Y. Copin (eds)
EAS Publications Series, 36 (2009) 17-24
DOI: 10.1051/eas/0936003

Newtonian approach to the matter power spectrum of the generalized chaplygin gas

J.C. Fabris¹, S.V.B. Goncalves², H.E.S. Velten³ and W. Zimdahl⁴

¹ Universidade Federal do Espírito Santo, Departamento de Física, Av. Fernando Ferrari, 514 Campus de Goiabeiras, CEP 29075-910, Vitória, Espírito Santo, Brazil; ; : Institut d'Astrophysique de Paris - IAP, Paris, France
² Universidade Federal do Espírito Santo, Departamento de Física, Av. Fernando Ferrari, 514, Campus de Goiabeiras, CEP 29075-910, Vitória, Espírito Santo, Brazil; ; : Laboratoire d'Annecy-le-Vieux de Physique Théorique - LAPTH, Annecy-le-Vieux, France
³ Universidade Federal do Espírito Santo, Departamento de Física, Av. Fernando Ferrari, 514, Campus de Goiabeiras, CEP 29075-910, Vitória, Espírito Santo, Brazil;
⁴ Universidade Federal do Espírito Santo, Departamento de Física Av. Fernando Ferrari, 514 Campus de Goiabeiras, CEP 29075-910, Vitória, Espírito Santo, Brazil;

fabris@cce.ufes.br
sergio.vitorino@pq.cnpq.br
velten@cce.ufes.br
zimdahl@thp.uni-koeln.de

Published online: 30 May 2009

Abstract
We model the cosmic medium as the mixture of a generalized Chaplygin gas and a pressureless matter component. Within a neo-Newtonian approach we compute the matter power spectrum. The 2dFGRS data are used to discriminate between unified models of the dark sector and different models, for which there is separate dark matter, in addition to that accounted for by the generalized Chaplygin gas. Leaving the corresponding density parameters free, we find that the unified models are strongly disfavored. On the other hand, using unified model priors, the observational data are also well described, in particular for small and large values of the generalized Chaplygin gas parameter $\alpha$ .

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