SUPERSYMMETRIC, COLD AND LUKEWARM BLACK-HOLES IN COSMOLOGICAL EINSTEIN-MAXWELL THEORY

In asymptotically flat (AF) space, the extreme Reissner-Nordstrom (RN) black hole is distinguished by its coldness (vanishing Hawking temperature) and its supersymmetry. We examine RN solutions to Einstein-Maxwell theory with a cosmological constant LAMBDA, classifying the cold black holes and, for positive LAMBDA, the "lukewarm" black holes at the same temperature as the de Sitter thermal background. For negative LAMBDA, we classify the supersymmetric solutions within the context of N = 2 gauged supergravity. One finds supersymmetric analogues of AF-space extreme RN black holes, which for nonzero LAMBDA differ from the cold black holes. In addition, these is an exotic class of supersymmetric solutions which cannot be continued to asymptotically flat space. since the magnetic charge becomes infinite in that limit.