Unified and bouncing cosmologies with inhomogeneous viscous fluid

Singh, Ashutosh; Chaubey, R.

doi:10.1007/s10509-021-03921-x

Cited by 15 publications

(5 citation statements)

References 58 publications

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“…The de Sitter, accelerating power-law expansion can be achieved for q = −1 and −1 < q < 0 respectively. For q < −1, super-exponential expansion scenario exists [45][46][47][48][49]. It have been confirmed by observational results that the universe is currently expanding with acceleration and it has been decelerating in the past [50].…”

Section: Cosmological Equationsmentioning

confidence: 93%

Qualitative study of anisotropic Rastall cosmologies

Singh,

Pradhan

2022

Preprint

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We perform dynamical analysis of anisotropic Rastall cosmologies and, in particular Kantowski-Sachs, locally rotationally symmetric (LRS) Bianchi I and LRS Bianchi III cosmologies. Using dynamical system techniques, a qualitative analysis of cosmological equations yield physically interesting cases which are in agreement with observations such as de Sitter, accelerating, stable attractors are isotropic. Features such as isotropization and cosmological bounce are discussed in detail.

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Section: Cosmological Equationsmentioning

confidence: 93%

Qualitative study of anisotropic Rastall cosmologies

Singh,

Pradhan

2022

Preprint

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“…For q < −1, q = −1 and −1 < q < 0, universe will undergo super-exponential, de Sitter and accelerated expansion respectively. Eternal acceleration is achieved when q < 0 for all time and the universe decelerates for q > 0 [ [48][49][50][51]. For variables x, y (see Eq.…”

Section: (1+α)mentioning

confidence: 99%

Cosmic dynamics and qualitative study of Rastall model with spatial curvature

Singh,

Pradhan

2022

Preprint

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We investigate the cosmic dynamics of Rastall gravity in non-flat Friedmann-Robertson-Walker (FRW) space-time with barotropic fluid. In this context, we are concerned about the class of model satisfying the affine equation of state. We derive the autonomous system for the Rastall model with barotropic fluid. We apply the derived system to investigate the critical points for expanding and bouncing cosmologies and their stable nature and cosmological properties. The expanding cosmology yields de Sitter universe at late times with decelerating past having matter and radiation dominated phases. Investigation of autonomous system for bouncing cosmology yields oscillating solutions in positive spatial curvature region. We also investigate the consequences of setting-up a model of non-singular universe by using energy conditions. The distinct features of the Rastall model compared to the standard model have been discussed in detail.

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“…Several studies have shown the profligacy of viscous fluids which includes the shear and bulk viscosity [32,[36][37][38][39]. In references [40][41][42][43][44][45][46][47][48][49][50], the impact of bulk viscous fluids in the late-time accelerating cosmos have been examined. However, in an expanding universe, a feasible process for viscous fluid formation is more difficult to find.…”

Section: Introductionmentioning

confidence: 99%

Quintessence Behavior of an Anisotropic Bulk Viscous Cosmological Model in Modified f(Q)-Gravity

2022

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In this article, we consider an anisotropic viscous cosmological model having LRS Bianchi type I spacetime with f(Q) gravity. We investigate the modified f(Q) gravity with form f(Q)=αQ2+β, where Q is the non-metricity scalar and α, β are the positive constants. From the modified Einstein’s field equation having the viscosity coefficient ξ(t)=ξ0H, the scale factor is derived as a(t)=2sinhm+26ξ0α(2m+1)t. We apply the observational constraints on the apparent magnitude m(z) using the χ2 test formula with the observational data set such as JLA, Union 2.1 compilation and obtained the best approximate values of the model parameters m,α,H0,ξ0. We find a transit universe which is accelerating at late times. We also examined the bulk viscosity equation of state (EoS) parameter ωv and derived its current value satisfying ωv<−1/3, which shows the dark energy dominating universe evolution having a cosmological constant, phantom, and super-phantom evolution stages. It tends to the Λ cold dark matter (ΛCDM) value (ωv=−1) at late times. We also estimate the current age of the universe as t0≈13.6 Gyrs and analyze the statefinder parameters with (s,r)→(0,1) as t→∞.

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Unified and bouncing cosmologies with inhomogeneous viscous fluid

Cited by 15 publications

References 58 publications

Qualitative study of anisotropic Rastall cosmologies

Qualitative study of anisotropic Rastall cosmologies

Cosmic dynamics and qualitative study of Rastall model with spatial curvature

Quintessence Behavior of an Anisotropic Bulk Viscous Cosmological Model in Modified f(Q)-Gravity

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