Cosmological models with cubically varying deceleration parameter in f(R, T) gravity

Holographic dark energy in Gauss-Bonnet gravity with Granda-Oliveros cut-off

“…the cosmic microwave background (CMB) anomalies from the results obtained by Planck [49]. Several researchers have studied homogeneous and anisotropic Bianchi models, such as the spatially homogeneous and anisotropic Bianchi type-I model, which is a direct generalization of the FLRW Universe with a scale factor in each spatial direction [38,39]. In this paper, motivated by the work [35], we study the holographic model of DE under f (G) gravity in the Bianchi type-I Universe, to find solutions of the field equations and some physical quantities, we will assume that the deceleration parameter (DP) varies with time.…”

“…The coincidence parameter (r) can be defined as the ratio between the HDE density (ρ Λ ) and the matter energy density (ρ m ), therefore for Eqs. (38) and (39) the coincidence parameter becomes…”

Anisotropic f(Q) gravity model with bulk viscosity

“…As a result, more attractive dynamical models based on the principle of modifying matter content of the Universe have appeared, such as quintessence, k-essence, Chapylygin gas, holographic dark energy, etc [8][9][10][11]. Recently, with researchers interested in the issue of cosmic acceleration, other alternatives have emerged called modified theories of gravity (MTG), which aim to modify the standard Einstein-Hilbert action and replace Ricci scalar curvature R with arbitrary functions of this scalar f (R) [12,13], or other physical quantities, such as f (R, T ) gravity (where R is the Ricci scalar and T is the trace of the energymomentum tensor) [14][15][16], f (G) gravity (where G is the Gauss-Bonnet invariant) [17][18][19], f (T ) gravity (where T is the torsion scalal) [20][21][22], f (Q) gravity (Q is the nonmetricity scalar), etc. In this work, we will examine a cosmological model in order to explain the cosmic acceleration in the framework of f (Q) symmetric teleparallel gravity proposed by Jiménez et al [23], where the non-metricity scalar Q is responsible for the gravitational interaction in this theory.…”

Stability analysis of anisotropic Bianchi type-I cosmological model in teleparallel gravity

“…Recently, a new type of study has appeared, which attempts to explain the accelerated expansion of the Universe by assuming cosmological models in various gravitational theories that contain the deceleration parameter or in another way the scale factor which varies over time [18][19][20]. Indeed, this hypothesis is supported by observational data which shows that the Universe has passed from the stage of early deceleration (q > 0) to the stage of current acceleration (q < 0).…”