Magnetized string cosmological models of accelerated expansion of the Universe in f(R, T) theory of gravity

A class of spatially homogeneous and anisotropic Bianchi-V massive string models have been studied in the modified f(R, T)-theory of gravity proposed by Harko et al. [Phys. Rev. D 84: 024020, 2011] in the presence of magnetic field. For a specific choice of f(R, T)= f(1)(R) + f(2)(T), where f(1)(R) = nu R-1 and f(2)(T) = nu T-2; nu(1), nu(2) being arbitrary parameters, solutions of modified gravity field equations have been generated. To find the deterministic solution of the field equations, we have considered the time varying deceleration parameter which is consistent with observational data of standard cosmology (SNIa, BAO and CMB). As a result to study the transit behavior of Universe, we consider a law of variation for the specifically chosen scale factor, which yields a time-dependent deceleration parameter comprising a class of models that depicts a transition of the Universe from the early decelerated phase to the recent accelerating phase. In this context, for the model of the Universe, the field equations are solved and corresponding cosmological aspects have been discussed. The Energy conditions in this modified gravity theory are also studied. Stability analysis of the solutions through cosmological perturbation is performed and it is concluded that the expanding solution is stable against the perturbation with respect to anisotropic spatial direction. Some physical and geometric properties of the models are also discussed.