Odd-parity gravity waves from the Regge–Wheeler gauge perspective in the f(R, T) theory

Abstract

We mainly intend to discuss the odd-parity (or axial) modes of gravity (or gravitational) waves (GWs) in the Regge–Wheeler formalism. Since, there are plenty of astrophysical data that lead us to a space-time structure entered in a speedy expansion epoch, we perform our analysis in the f(R, T) theory of gravity, where the gravitational Lagrangian is written as an arbitrary function of the Ricci scalar R and the trace of the stress-energy tensor T, from the rainbow formalism of gravity perspective. In our study, we start with perturbing the background metric, background material distribution and the four-velocity components via the Regge–Wheeler gauge. Subsequently, formulating the corresponding field equations for both unperturbed and perturbed forms of the spatially flat conformal Friedmann–Lemaitre–Robertson–Walker metric, we solve them simultaneously to find out exact expressions of the unknown perturbation functions. Also, we focus our attention on Huygens’ principle to discuss additional features of the odd-parity modes of GWs.