Horizons and singularity in Clifton’s spherical solution of f (R) vacuum

Abstract

Due to the failure of Birkhoff’s theorem, black holes in f (R) gravity theories in which an effective time-varying cosmological “constant” is present are, in general, dynamical. Clifton’s exact spherical solution of R1+δ gravity, which is dynamical and describes a central object embedded in a spatially flat universe, is studied. It is shown that apparent black hole horizons disappear and a naked singularity emerges at late times.