A Bianchi Type-VI0 cosmological model with a special form of scale factor is studied. Einstein field equations in Sen-Dunn theory are obtained and solved for exact solutions. This solution gives a scenario of the dark energy model which tends to a ɅCDM model. The physical and geometrical properties are also obtained and analyzed with the present day observations.

In this paper, we study the spatially homogeneous Robertson-Walker cosmological models with magnetized isotropic dark energy like fluid in the scalar-tensor theory of gravitation proposed by Brans-Dicke. Variable cosmological constant ᴧ and Polytropic equation of state have been used to find exact solutions of the models with volumetric expansion and power-law relation. The Physical and dynamical behaviors of the models have been discussed using some physical quantities like energy density, pressure, and coefficient of bulk viscosity.

Objectives: To investigate the Bianchi Type-III cosmological model in the presence of a magnetic field using the time-dependent deceleration parameter in Sen-Dunn scalar-tensor theory. Methods: In this work, we approach a Bianchi type-III metric with the presence of a magnetic field in the energymomentum tensor. The time-dependent deceleration parameter representing an accelerated expansion proposed by Banerjee and Das (Gen. Relativ. Gravit. 37:10, 2005)is applied to obtain the exact solution of the field equations. Also, to obtain a deterministic solution considering shear scalar proportional to scalar expansion resulting inB = C β . Furthermore, taking the power law relation between the scalar field and the average scale factor, the model's following physical and geometrical properties are computed and discussed with the present observational data. Findings:The model is anisotropic, expanding, shearing, and non-rotating with increasing volume as time tends to infinity from zero volume at t = 0. The model approves an accelerating universe under the ΛCDM model. Novelty: The study provides a better comprehension of cosmic evolution within the Sen-Dunn scalar-tensor gravitational theory context. The model demonstrates its consistency with the cosmological observation.

This paper deals with the bulk viscous Bianchi type-V cosmological model with an exponential scale factor in Lyra geometry based on f(R, T) gravity, by considering a time dependent displacement field. To determine the nature and physical properties of the model, we considered Harko et al. (Harko et al., Phys. Rev. D, 2011, 84, 024020) [proposed the linear form f(R, T) = f1(R) + f2(T)], in which the barotropic equation of state for pressure, density, and bulk viscous pressure is proportional to energy density. The kinematical properties of the model are also discussed in the presence of bulk viscosity. Evolution of energy conditions is also studied and examined the behaviour of that in examined in order to explain the late-time cosmic acceleration.

No abstract