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arXiv · 1012.4459

Unified models of the cosmological dark sector

W Zimdahl·W S Hipólito-Ricaldi·H E S Velten
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Abstract

We model the cosmological substratum by a viscous fluid that is supposed to provide a unified description of the dark sector and pressureless baryonic matter. In the homogeneous and isotropic background the \textit{total} energy density of this mixture behaves as a generalized Chaplygin gas. The perturbations of this energy density are intrinsically non-adiabatic and source relative entropy perturbations. The resulting baryonic matter power spectrum is shown to be compatible with the 2dFGRS and SDSS (DR7) data. A joint statistical analysis, using also Hubble-function and supernovae Ia data, shows that, different from other studies, there exists a maximum in the probability distribution for a negative present value $q_{0} \approx - 0.53$ of the deceleration parameter. Moreover, different from other approaches, the unified model presented here favors a matter content that is of the order of the baryonic matter abundance suggested by big-bang nucleosynthesis.

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W Zimdahl, W S Hipólito-Ricaldi, H E S Velten. 2010-12-20. Unified models of the cosmological dark sector. https://doi.org/10.1088/1742-6596%2F314%2F1%2F012057

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