Curvature singularities, tidal forces and the viability of Palatini f(R) gravity

Abstract

In a previous paper we showed that static spherically symmetric objects which, in the vicinity of their surface, are well-described by a polytropic equation of state with 3/2<Gamma<2 exhibit a curvature singularity in Palatini f(R) gravity. We argued that this casts serious doubt on the validity of Palatini f(R) gravity as a viable alternative to General Relativity. In the present paper we further investigate this characteristic of Palatini f(R) gravity in order to clarify its physical interpretation and consequences.

Comments: 15 pages. CQG in press. Part of the material moved to an appendix, discussion on the meV scale predictions of Palatini f(R) gravity added