Viscous dark fluid

Folomeev, Vladimir; Gurovich, V. Tz.

doi:10.1016/j.physletb.2008.01.068

Cited by 19 publications

(27 citation statements)

References 12 publications

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“…This model is built as a generalized form of the constant bulk viscosity studied in [46]. The second model contains a more complex form for the bulk viscosity that involves the tanh function that depends on the Hubble parameter E and was proposed by [53]. Finally, as an alternative to tanh form, we explore the Universe dynamics by proposing a cosh form for the bulk viscosity coefficient.…”

Section: Introductionmentioning

confidence: 99%

Cosmological test on viscous bulk models using Hubble parameter measurements and type Ia supernovae data

Hernández-Almada

2019

Eur. Phys. J. C

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From a phenomenological point of view, we analyze the dynamics of the Universe at late times by introducing a polynomial and hyperbolic bulk viscosity into the Einstein field equations respectively. We constrain their free parameters using the observational Hubble parameter data and the Type Ia Supernovae dataset to reconstruct the deceleration q and the jerk j parameters within the redshift region 0 < z < 2.5. At current epochs, we obtain q 0 = −0.680 +0.085 −0.102 and j 0 = 2.782 +1.198 −0.741 for the polynomial model and q 0 = −0.539 +0.040 −0.038 (−0.594 +0.056 −0.056 ) and j 0 = 0.297 +0.051 −0.050 (1.124 +0.196 −0.178 ) for the tanh (cosh) model. Furthermore, we explore the statefinder diagnostic that gives us evident differences with respect to the concordance model (LCDM). According to our results this kind of models is not supported by the data over LCDM.

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Section: Introductionmentioning

confidence: 99%

Cosmological test on viscous bulk models using Hubble parameter measurements and type Ia supernovae data

Hernández-Almada

2019

Eur. Phys. J. C

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“…[9,18,29,[31][32][33][34][35][36][37][38][39][40][41][42]. However, the perturbative analysis of the viscous cosmological models is not as widely addressed, despite its crucial importance.…”

Section: Introductionmentioning

confidence: 99%

Bulk viscous cosmology with causal transport theory

Piattella

Fabris

Zimdahl

2011

J. Cosmol. Astropart. Phys.

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Abstract. We consider cosmological scenarios originating from a single imperfect fluid with bulk viscosity and apply Eckart's and both the full and the truncated Müller-Israel-Stewart's theories as descriptions of the non-equilibrium processes. Our principal objective is to investigate if the dynamical properties of Dark Matter and Dark Energy can be described by a single viscous fluid and how such description changes when a causal theory (Müller-IsraelStewart's, both in its full and truncated forms) is taken into account instead of Eckart's non-causal theory. To this purpose, we find numerical solutions for the gravitational potential and compare its behaviour with the corresponding ΛCDM case. Eckart's and the full causal theory seem to be disfavoured, whereas the truncated theory leads to results similar to those of the ΛCDM model for a bulk viscous speed in the interval 10 −11 ≪ c 2 b 10 −8 . Tentatively relating such value to a square propagation velocity of the order of T /m of perturbations in a non-relativistic gas of particles with mass m at the epoch of matter-radiation equality, this may be compatible with a mass range 0.1 GeV m ≪ 100 GeV.

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“…In [39], authors assume the bulk viscosity takes the form as an Hubble parameter dependent function. A redshift-dependent viscosity is proposed in [28].…”

Section: A Redshift-dependent Modelmentioning

confidence: 99%

Bulk Viscous Cosmology: Unified Dark Matter

Dou

Meng

2011

Advances in Astronomy

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The bulk viscosity is introduced to model unified dark matter. The viscous unified model assumes the universe is filled with a single fluid with the bulk viscosity. We review the general framework of the viscous cosmology. The Hubble parameter has a direct connection with the bulk viscosity coefficient. For concrete form of the bulk viscosity, the Hubble parameter which has the scaling relation with the redshift can be obtained. We discuss two viscosity models and the cosmological evolution to which they lead. Using SNe Ia data, the viscosity model can be fitted. We briefly review the fitting method here. * Electronic address:

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Viscous dark fluid

Cited by 19 publications

References 12 publications

Cosmological test on viscous bulk models using Hubble parameter measurements and type Ia supernovae data

Cosmological test on viscous bulk models using Hubble parameter measurements and type Ia supernovae data

Bulk viscous cosmology with causal transport theory

Bulk Viscous Cosmology: Unified Dark Matter

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