Viscous dark fluid universe

Journal Article · Wed Sep 15 04:00:00 EDT 2010 · Physical Review. D, Particles Fields

DOI:https://doi.org/10.1103/PHYSREVD.82.063507· OSTI ID:21421114

Hipolito-Ricaldi, W S ^[1]; Velten, H E. S.; Zimdahl, W ^[2]

---

1. Universidade Federal do Espirito Santo, Departamento de Ciencias Matematicas e Naturais, CEUNES, Rodovia BR 101 Norte, km. 60, CEP 29932-540, Sao Mateus, Espirito Santo (Brazil)
2. Universidade Federal do Espirito Santo, Departamento de Fisica, Av. Fernando Ferrari, 514, Campus de Goiabeiras, CEP 29075-910, Vitoria, Espirito Santo (Brazil)

We investigate the cosmological perturbation dynamics for a universe consisting of pressureless baryonic matter and a viscous fluid, the latter representing a unified model 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 q{sub 0{approx_equal}}-0.53 of the deceleration parameter. Moreover, while previous descriptions on the basis of generalized Chaplygin-gas models were incompatible with the matter power-spectrum data since they required a much too large amount of pressureless matter, the unified model presented here favors a matter content that is of the order of the baryonic matter abundance suggested by big-bang nucleosynthesis.

• OSTI ID: 21421114
• Journal Information: Physical Review. D, Particles Fields, Journal Name: Physical Review. D, Particles Fields Journal Issue: 6 Vol. 82; ISSN PRVDAQ; ISSN 0556-2821
• Country of Publication: United States
• Language: English

Related Subjects

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
ACCELERATION
BARYONS
BINARY STARS
COSMOLOGICAL MODELS
DISTRIBUTION
DISTURBANCES
ELEMENTARY PARTICLES
ENERGY DENSITY
ENTROPY
ERUPTIVE VARIABLE STARS
FERMIONS
HADRONS
MATHEMATICAL MODELS
MATTER
NONLUMINOUS MATTER
NUCLEAR MODELS
NUCLEOSYNTHESIS
PERTURBATION THEORY
PHYSICAL PROPERTIES
SPECTRA
STARS
SUPERNOVAE
SYNTHESIS
THERMODYNAMIC PROPERTIES
UNIFIED MODEL
UNIVERSE
VARIABLE STARS