Mass inflation in 2d dilaton gravity

Abstract

Recently two-dimensional dilaton gravity has received great attention. We investigate two-dimensional charged black holes. These solutions possess two horizons, an event horizon and an inner, so-called Cauchy horizon. It has been argued on general grounds that the inner horizon must be unstable. We show that a minimally coupled scalar field indeed causes a mass inflation singularity to be formed at the Cauchy horizon, in striking similarity to the four-dimensional case.