Narrow Results

We have studied LRS Bianchi type I cosmological models with barotropic perfect fluid and cosmic string in the framework of $f(T)$ 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 $f(T)$ such as $f(T)=\eta {(-T)}^m+c,$$f(T)=e^{mT}$ and $f(T)=\gamma T+\eta T^m$ are chosen for investigation. It is observed that the universe is dominated by quintessence type dark energy. The universe is accelerating, expanding and anisotropic.

A study is made of the LRS Bianchi type-I cosmological model in $f(R,T)$ modified gravity theory. Einstein’s field equations in $f(R,T)$ gravity are solved by taking $f(R,T)=R+2f(T)$ and the deceleration parameter $(q)$ to be a linear function of the Hubble parameter $(H)$. The universe begins with an initial singular state and changes with time from an early deceleration phase to a late time acceleration phase. We have found that the jerk parameter $(j)$ in the model approaches that of the $\mathrm{\Lambda }CDM$ model at late times. We also discuss the physical and geometrical properties of the model.

LRS Bianchi type I space time is considered to explore bulk viscous string model in modified $f(G)$ gravity. Field equations are solved with some physically viable condition. It is observed that the string phase of the universe disappears. The Gauss–Bonnet invariant significantly effects on galactic fluid. The universe is expanding and isotropic at large time. Some physical parameters are also discussed in detail.

The present work deals with the dynamical evolution of LRS Bianchi type I (LRS BI) cosmological model with quadratic dark sector coupling. We investigate the phase-plane analysis of LRS BI model with dark energy, when dark energy is modeled as exponential quintessence, and is coupled to dark matter via energy exchange. The evolution of cosmological solutions are studied by using dynamical systems method. Stability and viability of the models are discussed for four different choices of quadratic dark sector coupling parameters. In each model, we have obtained a late-time accelerating fixed point (future attractor), which is not a scaling solution.