Stability criterion for white dwarfs in Palatini $f(R)$ gravity

TL;DR

This paper investigates the stability and mass limits of white dwarfs within Palatini $f(R)$ gravity, providing explanations for super- and sub-Chandrasekhar supernovae observations and establishing stability criteria.

Contribution

It derives super- and sub-Chandrasekhar mass limits and stability conditions for white dwarfs in Palatini $f(R)$ gravity, extending previous models beyond general relativity.

Findings

Super- and sub-Chandrasekhar mass limits are obtained.

The stability criterion $rac{ ext{d}M}{ ext{d} ho_c}>0$ remains valid.

White dwarf stability analysis is extended to Palatini $f(R)$ gravity.

Abstract

Recent observations of several peculiar over- and under-luminous type Ia supernovae infer indirect evidence for the violation of the Chandrasekhar mass-limit by suggesting the existence of super- and sub-Chandrasekhar limiting mass white dwarfs. In an attempt to explain these phenomena in the context of general relativistic extensions, we study these objects in Palatini $f(R)$ gravity. We obtain the super- and sub-Chandrasekhar limiting masses as well as the dynamical instability criteria for white dwarfs in the given gravitational theory. We further demonstrate that the conventional positivity condition $\partial{M}/\partial{\rho_\text{c}}>0$ with $M$ being the WD's mass with central density $\rho_\text{c}$, is also a valid criterion for stability in Palatini gravity.