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

Abstract

Recent observations of several peculiar over- and underluminous 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 ∂M/∂ρc>0 with M being the WD’s mass with central density ρc is also a valid criterion for stability in Palatini gravity.