Polar gravitational waves in f(R, Tf) framework

This work analyzes the propagation of polar gravitational waves for flat FRW cosmic background and in view of f(R, T-f ) theory. In what follows, we opt for the Regge-Wheeler polar perturbation scheme in flat geometry of background spacetime and corresponding scalar, field source is also perturbed. The two sets of field equations for flat and perturbed geometry are constructed and furthermore used to evaluate perturbation parameters. The obtained expressions suggest that polar fluctuations affect both geometry and scalar field. The radial and temporal parts of perturbation parameters ? and s are plotted explicitly while the behavior of ? is observed via a numerical solution plotted as a 3D graph. The change in these fluctuations for different values of model parameter ? is noticed through these plots.