Abstract
A nonextreme black hole in a cavity within the framework of the canonical or grand canonical ensemble can approach the extreme limit with a finite temperature measured on a boundary located at a finite proper distance from the horizon. In spite of this finite temperature, it is shown that the one-loop contribution of quantum fields to the thermodynamic entropy due to equilibrium Hawking radiation vanishes in the limit under consideration. The same is true for the finite temperature version of the Bertotti-Robinson spacetime into which a classical Reissner-Nordström black hole turns in the extreme limit. The result is attributed to the nature of a horizon for the Bertotti-Robinson spacetime.
- Received 30 May 1997
DOI:https://doi.org/10.1103/PhysRevD.57.6265
©1998 American Physical Society