Shear-free condition and dynamical instability in f(R, T) gravity

The implications of the shear-free condition on the instability range of an anisotropic fluid in f(R, T) are studied in this manuscript. A viable f(R, T) model is chosen to arrive at stability criterion, where R is Ricci scalar and T is the trace of energy-momentum tensor. The evolution of a spherical star is explored by employing a perturbation scheme on the modified field equations and contracted Bianchi identities in f(R, T). The effect of the imposed shear-free condition on the collapse equation and adiabatic index Γ is studied in the Newtonian and post-Newtonian regimes. (orig.)