Perturbations of charged black holes

Abstract

Wave equations are derived in the Newman-Penrose formalism for gravitational and electromagnetic perturbations produced by charged and uncharged matter moving in a Reissner-Nordstr\"om background geometry. A brief sketch is given to obtain similar sets of equations in the Kerr-Newman background. The wave equations in the Kerr-Newman background, however, do not seem to separate, at least for the variables and the coordinate system used here.