Constraints on dissipative unified dark matter

Velten H, Schwarz D (2011)
Journal of Cosmology and Astroparticle Physics 2011(09).

Journal Article | Published | English

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Abstract
Modern cosmology suggests that the Universe contains two dark components -- dark matter and dark energy -- both unkown in laboratory physics and both lacking direct evidence. Alternatively, a unified dark sector, described by a single fluid, has been proposed. Dissipation is a common phenomenon in nature and it thus seems natural to consider models dominated by a viscous dark fluid. We focus on the study of bulk viscosity, as isotropy and homogeneity at large scales implies the suppression of shear viscosity, heat flow and diffusion. The generic ansatz ξ∝ρν for the coefficient of bulk viscosity (ρ denotes the mass/energy density), which for ν=−1/2 mimics the ΛCDM background evolution, offers excellent fits to supernova and H(z) data. We show that viscous dark fluids suffer from large contributions to the integrated Sachs-Wolfe effect (generalising a previous study by Li & Barrow) and a suppression of structure growth at small-scales (as seen from a generalized Meszaros equation). Based on recent observations, we conclude that viscous dark fluid models (with ξ∝ρν and neglecting baryons) are strongly challenged.
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Velten H, Schwarz D. Constraints on dissipative unified dark matter. Journal of Cosmology and Astroparticle Physics. 2011;2011(09).
Velten, H., & Schwarz, D. (2011). Constraints on dissipative unified dark matter. Journal of Cosmology and Astroparticle Physics, 2011(09).
Velten, H., and Schwarz, D. (2011). Constraints on dissipative unified dark matter. Journal of Cosmology and Astroparticle Physics 2011.
Velten, H., & Schwarz, D., 2011. Constraints on dissipative unified dark matter. Journal of Cosmology and Astroparticle Physics, 2011(09).
H. Velten and D. Schwarz, “Constraints on dissipative unified dark matter”, Journal of Cosmology and Astroparticle Physics, vol. 2011, 2011.
Velten, H., Schwarz, D.: Constraints on dissipative unified dark matter. Journal of Cosmology and Astroparticle Physics. 2011, (2011).
Velten, Hermano, and Schwarz, Dominik. “Constraints on dissipative unified dark matter”. Journal of Cosmology and Astroparticle Physics 2011.09 (2011).
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