Semiclassical Decay of Near-Extremal Black Holes

Decay of a near-extremal black hole down to the extremal state is studied in the background field approximation to determine the fate of injected matter and Hawking pairs. By examining the behavior of light rays and solutions to the wave equation it is concluded that the singularity at the origin is irrelevant. Furthermore, there is most likely an instability of the event horizon arising from the accumulation of injected matter and Hawking partners there. The possible role of this instability in reconciling the D-brane and black hole pictures of the decay process is discussed.