Study of nonstatic anisotropic axial structures through perturbation

Abstract

This work is related to the stability of a nonstatic, very restricted class of axially symmetric cosmic matter configuration under the influence of modified gravitational theory (AGT) with a realistic model in anisotropic conditions. We construct dynamically modified equations, continuity equations, mass functions and collapse equations in the scenario of considered AGT. We continue our analysis under the influence of f(R,T) gravity along with a minimally coupled gravitational function of the form [Formula: see text], where [Formula: see text] indicates constant entity. In this gravitational model, f is a function of Ricci scalar invariant R and the trace of the stress–energy tensor T. This gravitational function gives significant findings only for [Formula: see text], and both belong to the set of positive real numbers and also [Formula: see text]. We establish expressions of an adiabatic index, i.e. stiffness parameter of fluid [Formula: see text] utilizing relevant perturbation technique with the help of collapse equation in Newtonian [Formula: see text] and post-Newtonian [Formula: see text] domains. We consider the particular form of metric as well as material functions in [Formula: see text] and [Formula: see text] eras, and impose some constraints on physical quantities (i.e. pressure, density, mass, etc.) to carry out the stable behavior of a considered restricted geometry.