Late-time viscous cosmology in f(R, T) gravity

Abstract

The article communicates an alternative route to suffice the late-time acceleration considering a bulk viscous fluid with viscosity coefficient ζ = ζ 0 + ζ 1 H + ζ 2 H 2 , where ζ 0 , ζ 1 , ζ 2 are constants in the framework of f (R, T) modified gravity. We presume the f (R, T) functional form to be f = R + 2αT where α is a constant. We then solve the field equations for the Hubble Parameter and study the cosmological dynamics of kinematic variables such as deceleration, jerk, snap and lerk parameters as a function of cosmic time. We observe the deceleration parameter to be highly sensitive to α and undergoes a signature flipping at around t ∼ 10 Gyrs for α = −0.179 which is favored by observations. The EoS parameter for our model assumes values close to −1 at t 0 = 13.7Gyrs which is in remarkable agreement with the latest Planck measurements. Next, we study the evolution of energy conditions and find that our model violate the Strong Energy Condition in order to explain the late-time cosmic acceleration. To understand the nature of dark energy mimicked by the bulk viscous baryonic fluid, we perform some geometrical diagnostics like the {r, s} and {r, q} plane. We found the model to mimic the nature of a Chaplygin gas type dark energy model at early times while a Quintessence type in distant future. Finally, we study the violation of continuity equation for our model and show that in order to explain the cosmic acceleration at the present epoch, energymomentum must violate.

Cosmological constraints on bulk viscous f(Q,T) gravity

“…Thus, to get the solution it is necessary to assume that the fluid is bulk viscous to simplify calculations. Moreover, it is a handful to assume that the fluid is described by the following Equation of State (further -just EoS) (Arora et al 2021a):…”

“…Also, we could express the bulk viscosity parameter in terms of Hubble parameter and it is derivatives (Arora et al 2021a;Gadbail et al 2021b):…”

“…Thus, to get the solution it is necessary to assume that the fluid is bulk viscous to simplify calculations. Moreover, it is a handful to assume that the fluid is described by the following Equation of State (further ‐ just EoS) (Arora et al 2021a): Where (for similar to ours scenario but with DM‐DE unification (dust fluid, ), check reference (Arora et al 2022)). B.…”

Inflation in f(R, T) gravity

“…The purpose of the present article is to investigate inflationary cosmological solutions consistent with latest Planck and BICEP2/Keck Array data in the framework of mimetic f (R, T ) gravity with Lagrange multiplier and mimetic potential. f (R, T ) gravity was introduced in [30] and has been extremely successful in the understanding of the flat rotation curves [31], late-time acceleration [30], baryogenesis [32], bouncing cosmology [33,34], evolution of density perturbations [35], redshift drift [36], Big bang nucleosynthesis [37], temporally varying physical constants [38], inflation [20,21], and viscous cosmology [39]. The manuscript is organized as follows: In Section II, we provide an overview of mimetic f (R, T ) gravity.…”

Bulk Viscous Bianchi Type-V Cosmological Model in f(R, T) Theory of Gravity

“…But in a recent cosmological model, f(R) gravity has become a more attractive theory to represent the behaviour of the expansion of the universe, known as f(R, T) gravity, where the matter Lagrangian is given by an arbitrary function of the Ricci scalar R and the trace of the energy momentum tensor T. Recently, Rao (Rao and Papa Rao, 2015), Kanakavalli (Kanakavalli et al, 2016), Sahoo (Sahoo et al, 2017), Nath (Nath and Sahu, 2019), and Sharma (Sharma et al, 2019), investigated the nature of the universe in f(R, T) gravity in different cosmological models in various space times. Very recently, Arora (Arora et al, 2021) discussed the late-time viscous cosmology in f(R, T) gravity considering a bulk viscous fluid with viscosity coefficient.…”