Nonsingular black hole evaporation and ‘‘stable’’ remnants

We examine the evaporation of two-dimensional black holes, the classical space-times of which are extended geometries, such as, for example, the two-dimensional section of the extremal Reissner-Nordstr\"om black hole. We provide evidence that the evaporation in two particular models proceeds to a stable end point. This should represent the generic behavior of a certain class of two-dimensional dilaton-gravity models. There are two distinct regimes depending on whether the back reaction is weak or strong in a certain sense. When the back reaction is weak, evaporation appears to proceed via an adiabatic evolution, whereas for strong back reaction, the decay proceeds in a somewhat surprising manner. Although information loss is inevitable in these models at the semiclassical level, it is rather benign, in that the information is stored in another asymptotic region.