Dynamical Instability of Shear-free Collapsing Star in Extended Teleparallel Gravity

TL;DR

This paper investigates the dynamical instability of shear-free, collapsing stars within extended teleparallel gravity, analyzing how physical parameters influence stability limits in Newtonian and post-Newtonian regimes.

Contribution

It introduces a perturbation framework in extended teleparallel gravity to analyze star collapse stability, considering non-diagonal tetrads and anisotropic matter.

Findings

Derived instability conditions depending on physical quantities.

Identified stability ranges in Newtonian and post-Newtonian regimes.

Provided constraints on physical parameters for stability.

Abstract

We study the spherically symmetric collapsing star in terms of dynamical instability. We take the framework of extended teleparallel gravity with non-diagonal tetrad, power-law form of model presenting torsion and matter distribution as non-dissipative anisotropic fluid. The vanishing shear scalar condition is adopted to search the insights of collapsing star. We apply first order linear perturbation scheme to metric, matter and $f(T)$ functions. The dynamical equations are formulated under this perturbation scheme to develop collapsing equation for finding dynamical instability limits in two regimes such as Newtonian and post-Newtonian. We obtain constraint free solution of perturbed time dependent part with the help of vanishing shear scalar. The adiabatic index exhibits the instability ranges through second dynamical equation which depend on physical quantities such as density, pressure components, perturbed parts of symmetry of star, etc. We also develop some constraints on positivity of these quantities and obtain instability ranges to satisfy the dynamical instability condition.