A universal lower bound on the specific temperatures of AdS-Reissner-Nordström black holes with flat event horizons

Abstract

We show that, in a gravitational theory [in any number of dimensions greater than 3] which admits BPS branes and AdS-Reissner-Nordström black holes with flat event horizons, the specific [dimensionless] temperature of such a black hole is bounded below by ≈0.156875. This confirms the recent suggestion by Hartnoll and Tavanfar, to the effect that no such black hole can be arbitrarily cold, since from the AdS/CFT dual point of view the low-temperature degrees of freedom should not be concealed by the equivalent of an event horizon. © 2011 Elsevier B.V.