Anisotropic Universe in f(G,T)f(\mathcal{G},\textit{T}) Gravity

This paper is devoted to investigate the recently introduced $f(\mathcal{G},\textit{T})$ theory of gravity, where $\mathcal{G}$ is the Gauss-Bonnet term, and ${\textit{T}}$ is the trace of the energy-momentum tensor. For this purpose, anisotropic background is chosen and a power law $f(\mathcal{G},\textit{T})$ gravity model is used to find the exact solutions of field equations. In particular, a general solution is obtained which is further used to reconstruct some important solutions in cosmological contexts. The physical quantities like energy density, pressure, and equation of state parameter are calculated. A Starobinsky Like $f_2(\textit{T})$ model is proposed which is used to analyze the behavior of universe for different values of equation of state parameter. It is concluded that presence of term $\textit{T}$ in the bivariate function $f(\mathcal{G},\textit{T})$ may give many cosmologically important solutions of the field equations.Comment: 20 pages, 10 figures, minor change

Locally Rotationally Symmetric Bianchi Type II Cosmology in f(R,T)f(R,T) Gravity

This manuscript is devoted to investigate Bianchi Type $I$ universe in the context of $f(R,T)$ gravity. For this purpose, we explore the exact solutions of locally rotationally symmetric Bianchi type $I$ spacetime. The modified field equations are solved by assuming expansion scalar $\theta$ proportional to shear scalar $\sigma$ which gives $A=B^n$, where $A,\,B$ are the metric coefficients and $n$ is an arbitrary constant. In particular, three solutions have been found and physical quantities are calculated in each case.Comment: 20 Pages, accepted for publication in EPJ

Dissipative Cylindrical Collapse of a Charged Anisotropic Fluid in f(R)f(R) Gravity

This paper is devoted to investigate the cylindrical collapse of an anisotropic fluid in $f(R)$ gravity. For this purpose, the viscous charged anisotropic fluid dissipating energy with heat flow and shear is assumed. We use the perturbation scheme to develop the dynamical equations for the variables that ultimately lead to the disturbance of the physical variables and the Starobinksy like $f(R)$ model chosen. The evolution of the matter variables is discussed with the help of these equations. It can be concluded that the range of dynamic instabilities depends on the field strength, density distribution, pressure and the curvature term of the $f(R)$ model. We find that our results of Newtonian and post-Newtonian regimes reduce asymptotically to general relativity solutions in the limiting case.Comment: 20 pages, accepted for publication in Canadian Journal of Physic

Physical Attributes of Anisotropic Compact Stars in f(R,G)f(R,G) Gravity

Modified gravity is one of the potential candidates to explain the accelerated expansion of the universe. Current study highlights the materialization of anisotropic compact stars in the context of $f(R,G)$ theory of gravity. In particular, to gain insight in the physical behavior of three stars namely, Her $X1$, SAX J $1808$-$3658$ and 4U $1820$-$30$, energy density, and radial and tangential pressures are calculated. The $f(R,G)$ gravity model is split into a Starobinsky like $f(R)$ model and a power law $f(G)$ model. The main feature of the work is a $3$-dimensional graphical analysis in which, anisotropic measurements, energy conditions and stability attributes of these stars are discussed. It is shown that all three stars behave as usual for positive values of $f(G)$ model parameter $n$.Comment: 21 pages, revised version, to appear in EPJ