Viscous accelerating universe with nonlinear and logarithmic equation of state fluid

Brevik, Iver; Макаренко, А. Н.; Тимошкин, А. В.

doi:10.1142/s0219887819501500

Cited by 8 publications

(6 citation statements)

References 54 publications

(55 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In the second case, the models that can describe the latetime accelerated expansion of the Universe are considered [33][34][35][36][37][38][39][40][41][42][43][44][45][46]. These models have revealed to be successful in reproducing the background evolution of the Universe at late time while attempting to solve the problems of CDM, unify or replace the dark components of the Universe and be compatible with the large structure formation.…”

Section: Introductionmentioning

confidence: 99%

Ricci cosmology in light of astronomical data

2021

View full text Add to dashboard Cite

Recently, a new cosmological framework, dubbed Ricci cosmology, has been proposed. Such a framework has emerged from the study of relativistic dynamics of fluids out of equilibrium in a curved background and is characterised by the presence of deviations from the equilibrium pressure in the energy–momentum tensor which are due to linear terms in the Ricci scalar and the Ricci tensor. The coefficients in front of such terms are called the second order transport coefficients and they parametrise the fluid response to the pressure terms arising from the spacetime curvature. Under the preliminary assumption that the second order transport coefficients are constant, we find the simplest solution of Ricci cosmology in which the presence of pressure terms causes a departure from the perfect fluid redshift scaling for matter components filling the Universe. In order to test the viability of this solution, we make four different ansätze on the transport coefficients, giving rise to four different cases of our model. On the physical ground of the second law of thermodynamics for fluids with non-equilibrium pressure, we find some theoretical bounds (priors) on the parameters of the models. Our main concern is then the check of each of the case against the standard set of cosmological data in order to obtain the observational bounds on the second order transport coefficients. We find those bounds also realising that Ricci cosmology model is compatible with $$\Lambda $$ Λ CDM cosmology for all the ansätze.

show abstract

Section: Introductionmentioning

confidence: 99%

Ricci cosmology in light of astronomical data

2021

View full text Add to dashboard Cite

show abstract

“…Recently, the effect of bulk viscosity in cosmic evolution has been intensively investigated, for instance, one can check the references. [35][36][37][38][39][40][41][42] In this work, we are going to analyze the role of different bulk viscosity coefficients in cosmic evolution by considering f (Q) gravity. The paper is organized as follows.…”

Section: Introductionmentioning

confidence: 99%

“…Recently, the effect of bulk viscosity in cosmic evolution has been intensively investigated, for instance, one can check the references. [ 35–42 ]…”

Section: Introductionmentioning

confidence: 99%

Viscous Fluid Cosmology in Symmetric Teleparallel Gravity

Solanki

Rana

Mandal

et al. 2023

Fortschritte der Physik

View full text Add to dashboard Cite

In this article, the viscous fluid cosmological model is analyzed in the framework of recently proposed gravity by assuming three different forms of bulk viscosity coefficients, specifically, , , and and a linear model, particularly, where is free model parameter. The bulk viscosity coefficients and the model parameter values using the combined H(z)+Pantheon+BAO data set are estimated. The asymptotic behavior of our cosmological bulk viscous model is studied by utilizing the phase space method. It is found that corresponding to all three cases, our model depicts the evolution of the universe from matter dominated decelerated epoch (a past attractor) to a stable de‐sitter accelerated epoch (a future attractor). Furthermore, the physical behavior of effective pressure, effective equation of state (EoS), and the statefinder parameters are studied. It is also found that the pressure component in the presence of bulk viscosity shows negative behavior and the effective EoS parameter predicts the accelerated expansion phase of the universe for all three cases. Moreover, the trajectories of the model lie in the quintessence region and it converges to the ΛCDM fixed point in the far future. It is found that the accelerated de‐Sitter like phase comes purely from the case without any geometrical modification to GR. Moreover, the late‐time behavior of all three cases of viscosity coefficients are identical. Furthermore, a non‐linear model is considered, specifically, , and then analyzed the behavior of model using dynamical approach. It is also found that the late‐time behavior of the considered non‐linear model with is similar to the linear case, whereas for the case results are quite different.

show abstract

“…Basically, the geometrical modification in the Einstein-Hilbert action of GR justifies the cosmic expansion, whereas the viscosity coefficients contribute to the pressure term to drive the cosmic acceleration. Recently, the effect of bulk viscosity in cosmic evolution has been intensively investigated, for instance, one can check the references [35][36][37][38][39][40][41][42].…”

Section: Introductionmentioning

confidence: 99%

Viscous fluid cosmology in symmetric teleparallel gravity

Solanki¹,

Rana²,

Mandal³

et al. 2022

Preprint

View full text Add to dashboard Cite

In this manuscript, we analyze the viscous fluid cosmological model in the framework of recently proposed f (Q) gravity by assuming three different forms of bulk viscosity coefficients, specifically,a , and (iii)ζ = ζ 0 and a linear f (Q) model, particularly, f (Q) = αQ where α = 0 is free model parameter. We estimate the bulk viscosity coefficients and the model parameter values using the combined H(z)+Pantheon+BAO data set. We study the asymptotic behavior of our cosmological bulk viscous model by utilizing the phase space method. We find that corresponding to all three cases, our model depicts the evolution of the universe from matter dominated decelerated epoch (a past attractor) to a stable de-sitter accelerated epoch ( a future attractor). Further, we study the physical behavior of effective pressure, effective equation of state (EoS), and the statefinder parameters. We find that the pressure component in the presence of bulk viscosity shows negative behavior and the effective EoS parameter predicts the accelerated expansion phase of the universe for all three cases. Moreover, we obtain that the trajectories of our model lie in the quintessence region and it converges to the ΛCDM fixed point in the far future. Thus we can conclude that our viscous fluid cosmological model can efficiently describe late time accelerated expansion phase of the universe corresponding to all three cases.

show abstract

Viscous accelerating universe with nonlinear and logarithmic equation of state fluid

Cited by 8 publications

References 54 publications

Ricci cosmology in light of astronomical data

Ricci cosmology in light of astronomical data

Viscous Fluid Cosmology in Symmetric Teleparallel Gravity

Viscous fluid cosmology in symmetric teleparallel gravity

Contact Info

Product

Resources

About