de Sitter Black Holes, Schottky Peaks, and Continuous Heat Engines

Understand

Recent work has uncovered Schottky-like peaks in the temperature dependence of key specific heats of certain black hole thermodynamic systems.

• They signal a finite window of available energy states for the underlying microscopic degrees of freedom.
• This paper reports on new families of peaks, found for the Kerr and Reissner-Nordstrom black holes in a spacetime with positive cosmological constant.
• It is known that a system with a highest energy, when coupled to two distinct heat baths, can naturally generate a thermodynamic instability, population inversion, a channel for work output.