Nonsingular colliding wave solutions in Einstein-Maxwell-dilaton-axion theory

Abstract

The local isometry between black holes and colliding plane waves is employed to derive new colliding wave solutions in the Einstein-Maxwell-dilaton-axion theory. The technique is applied to the asymptotically nonflat linear dilaton black holes. We obtain two new metrics which we label (from the language of black holes) as Kerr and Newman-Unti-Tamburino (NUT) types. The NUT type turns out to be type D while the Kerr type belongs to the general class. Both types share the common feature that, instead of an all encompassing generic singularity, Cauchy horizons develop in the process of collision.