Bulk viscous cosmology with causal transport theory

Piattella, Oliver F.; Fabris, J. C.; Zimdahl, Winfried

doi:10.1088/1475-7516/2011/05/029

Cited by 84 publications

(89 citation statements)

References 62 publications

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“…A recent investigation showed, that, at least for the Eckart theory applied here, the time dependence of the gravitational potential differs dramatically from the corresponding dependence of the ΛCDM model. 10 This confirms an earlier analysis in Ref. 9 and severely weakens the status of a viscous dark-sector model.…”

Section: Viscous Fluid and Gravitational Potentialsupporting

confidence: 87%

Viscous Dark Fluid Universe: A Unified Model of the Dark Sector?

Zimdahl

Velten

Hipólito-Ricaldi

2011

Int. J. Mod. Phys. Conf. Ser.

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The Universe is modeled as consisting of pressureless baryonic matter and a bulk viscous fluid which is supposed to represent a unified description of the dark sector. In the homogeneous and isotropic background the total energy density of this mixture behaves as a generalized Chaplygin gas. The perturbations of this energy density are intrinsically nonadiabatic 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 of the deceleration parameter. Moreover, the unified model presented here favors a matter content that is of the order of the baryonic matter abundance suggested by big-bang nucleosynthesis. A problem of simple bulk viscous models, however, is the behavior of the gravitational potential and the reproduction of the CMB power spectrum.

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Section: Viscous Fluid and Gravitational Potentialsupporting

confidence: 87%

Viscous Dark Fluid Universe: A Unified Model of the Dark Sector?

Zimdahl

Velten

Hipólito-Ricaldi

2011

Int. J. Mod. Phys. Conf. Ser.

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“…ρ v corresponds to the energy density of the bulk viscosity fluid and its present day value is denoted by the subscript 0. In general, this ansatz leads to a large amplification of the ISW signal [15,17,43]. However, this problem is less severe if s = 0 (ζ = const) and s = −1/2 [17].…”

Section: The Modelmentioning

confidence: 99%

Bulk viscosity, interaction and the viability of phantom solutions

Leyva¹,

Sepúlveda²

2017

Eur. Phys. J. C

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We study the dynamics of a bulk viscosity model in the Eckart approach for a spatially flat FriedmannRobertson-Walker (FRW) Universe. We have included radiation and dark energy, assumed as perfect fluids, and dark matter treated as an imperfect fluid having bulk viscosity. We also introduce an interaction term between the dark matter and dark energy components. Considering that the bulk viscosity is proportional to the dark matter energy density and imposing a complete cosmological dynamics, we find bounds on the bulk viscosity in order to reproduce a matterdominated era (MDE). This constraint is independent of the interaction term. Some late time phantom solutions are mathematically possible. However, the constraint imposed by a MDE restricts the interaction parameter, in the phantom solutions, to a region consistent with a null value, eliminating the possibility of late time stable solutions with w < −1. From the different cases that we study, the only possible scenario, with bulk viscosity and interaction term, belongs to the quintessence region. In the latter case, we find bounds on the interaction parameter compatible with latest observational data.

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“…In this work, we follow the recent results obtained in [13,14,15] and stick to the same choice for the bulk viscous coefficient…”

Section: Background Dynamicsmentioning

confidence: 99%

“…However, the integrated Sachs-Wolfe (ISW) effect of such models severely plagues models dominated by the VDF [13,14,15]. The reason of such pathology is very simple: the bulk viscosity induces a large time variation of the gravitational potential at late times.…”

Section: Introductionmentioning

confidence: 99%

Dissipation of dark matter

2012

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Fluids often display dissipative properties. We explore dissipation in the form of bulk viscosity in the cold dark matter fluid. We constrain this model using current data from supernovae, baryon acoustic oscillations and the cosmic microwave background. Considering the isotropic and homogeneous background only, viscous dark matter is allowed to have a bulk viscosity 10 7 Pa·s, also consistent with the expected integrated Sachs-Wolfe effect (which plagues some models with bulk viscosity). We further investigate the small-scale formation of viscous dark matter halos, which turns out to place significantly stronger constraints on the dark matter viscosity. The existence of dwarf galaxies is guaranteed only for much smaller values of the dark matter viscosity, 10 −3 Pa·s. PACS numbers: 98.80-k, 95.36+x

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Bulk viscous cosmology with causal transport theory

Cited by 84 publications

References 62 publications

Viscous Dark Fluid Universe: A Unified Model of the Dark Sector?

Viscous Dark Fluid Universe: A Unified Model of the Dark Sector?

Bulk viscosity, interaction and the viability of phantom solutions

Dissipation of dark matter

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