Kerr-Newman Black Holes and Negative Temperatures

Abstract

The application of the Unruh procedure to the Rindler approximation of the Kerr-Newman metric in the neighborhood of the event and Cauchy horizons leads, unambiguously, to the well-known positive Hawking (black hole) temperature at the outer horizon, but to a negative (white hole) temperature at the inner horizon. Some consequences for the heat capacities and the status of the third law of thermodynamics are also discussed.