EVOLUTION OF PERTURBATIONS INSIDE A CHARGED BLACK-HOLE - LINEAR SCALAR HELD

We present a simple method for the analysis of perturbations inside a charged black hole, to which we refer as the late-time expansion. This method has the advantage that it can be straightforwardly applied to nonlinear perturbations as well. It can also be generalized to (linear and nonlinear) metric perturbations in Kerr spacetime, allowing the i nvestigation of the singularity at the inner horizon of a generically perturbed spinning black hole. In this paper we describe, in full deta il, the application of our method to a linear scalar field on a Reissn er-Nordstrom background. In particular. we analyze the asymptotic beha vior near tile inner horizon. The scalar field itself is found to be f inite at the inner horizon, but its gradient diverges there. We compar e our results to those obtained previously by Gursel and co-workers an d by Chandrasekhar and Hartle (by a different method) and find full co nsistency.