Bianchi type I cosmological model with perfect fluid and string in f(T) theory of gravitation

We have studied LRS Bianchi type I cosmological models with barotropic perfect fluid and cosmic string in the framework of [Formula: see text] theory of gravitation. We have assumed that expansion of the model is proportional to the shear scalar. Hybrid law of expansion is also used to solve the field equations. Three different functional forms of the function [Formula: see text] such as [Formula: see text] [Formula: see text] and [Formula: see text] are chosen for investigation. It is observed that the universe is dominated by quintessence type dark energy. The universe is accelerating, expanding and anisotropic.

Accelerating Anisotropic Cosmological Model Filled with Two Fluid and ∧

In this paper we have studied Kantowski-Sachs universe filled with perfect fluid and radiation with a cosmological constant. To get determinate solution, it is assumed that the scalar of expansion is proportional to shear scalar (    ) which leads to the relation between metric potentials n R AS The cosmological parameters of models are also discussed.

Bianchi type-VI0 modified holographic Ricci dark energy model in a scalar–tensor theory

In this paper, we consider Bianchi type-VI0 space–time filled with anisotropic modified holographic Ricci dark energy in a scalar–tensor theory proposed by Brans–Dicke (Phys. Rev. 124, 925 (1961)). The field equations in this scalar–tensor theory, have been solved for the following physically relevant assumptions: (i) the scalar field ([Formula: see text]) is proportional to average scale factor (a(t)), (ii) expansion scalar (θ) in the model is proportional to shear scalar (σ). It has been observed that the presented universe is in an accelerating phase at the present epoch, which is in good agreement with the recent astronomical observations. We have also discussed some other properties of the obtained model.

Kantowski–Sachs scalar field cosmological models in a modified theory of gravity

In this paper, we investigate the anisotropic Kantowski–Sachs model in the f(R, T) theory of gravity proposed by Harko et al. (Phys. Rev. D, 84, 024020, 2011) with scalar field (quintessence or phantom). Here R is the Ricci scalar and T is the trace of the energy–momentum tensor. The field equations have been solved using the fact that scalar expansion is proportional to the shear scalar of the space–time. We explore the behavior of the deceleration parameter, which represents a transition of the universe from the early decelerating phase to the present accelerated phase. Some physical properties and various cosmological distance measures are also obtained and discussed.

Bianchi type VI0 generalized ghost pilgrim dark energy model in Brans–Dicke theory of gravitation

In this paper, we solve Brans–Dicke (BD) theory (Phys. Rev. D, 24, 925) field equations for anisotropic Bianchi type VI0 space–time and discuss evolution of the expanding Universe. Here, we consider pressureless fluid and isotropic generalized ghost pilgrim dark energy as the source of matter and dark energy, respectively. To get the determinate solution of the field equations we have used (i) scalar expansion proportional to the shear scalar and (ii) scalar field (in BD theory) proportional to average scale factor of the model. Some physical and geometrical properties of the model are also discussed.

Cosmological constant Λ in f(R,T) modified gravity

In this paper, we have studied the Bianchi type-III cosmological model in the presence of cosmological constant in the context of [Formula: see text] modified theory of gravity. Here, we have discussed two classes of [Formula: see text] gravity, i.e. [Formula: see text] and [Formula: see text]. In both classes, the modified field equations are solved by the relation expansion scalar [Formula: see text] that is proportional to shear scalar [Formula: see text] which gives [Formula: see text], where [Formula: see text] and [Formula: see text] are metric potentials. Also we have discussed some physical and kinematical properties of the models.

Kantowski-Sachs Cosmological model with quark and strange quark matter in f(R) theory of gravity

In this paper we have studied the Kantowski- Sachs cosmological model with the quark and strange quark matter in the f (R) theory of gravity. The general solutions of the field equations are obtained by assuming the physical condition shear scalar σ is proportional to scalar expansion θ, which leads to the relation B = An between metric coefficients B and A. The physical and geometrical aspects of the model are also discussed.

LRS Bianchi Type-I Inflationary String Cosmological Model in Brans-Dicke Theory of Gravitation

We investigate locally rotational symmetric (LRS) Bianchi type I space time coupled with scalar field. String cosmological models generated by a cloud of strings with particles attached to them are studied in the Brans-Dicke theory. We assume that the expansion scalar is proportional to the shear scalar and also power law ansatz for scalar field. The physical behavior of the resulting model is discussed through different parameters.

Bianchi type-II universe with linear equation of state

We have studied anisotropic and homogeneous Bianchi type-II cosmological model with linear equation of state (EoS) p = αρ−β, where α and β are constants, in General Relativity. In order to obtain the solutions of the field equations we have assumed the geometrical restriction that expansion scalar θ is proportional to shear scalar σ. The geometrical and physical aspects of the model are also studied.