Hermano Velten, Dominik J. Schwarz. Constraints on dissipative unified dark matter

Natural Sciences / Astronomy / Cosmology

Submitted on: Oct 10, 2012, 18:33:04

Description: 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 $xi propto rho^{nu}$ for the coefficient of bulk viscosity ($rho$ denotes the mass/energy density), which for $nu = - 1/2$ mimics the $Lambda$CDM 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. *** Published in JCAP09 (2011) 016 ***

The Library of Congress (USA) reference page : http://lccn.loc.gov/cn2013300046.

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