Cosmography of KNdS Black Holes and Isentropic Phase Transitions

Understand

We present a new analysis of Kerr-Newman-deSitter black holes in terms of thermodynamic quantities that are defined in the observable portion of the universe; between the black hole and cosmological horizons.

• In particular, we replace the mass $m$ with a new 'area product' parameter $X$.
• The physical region of parameter space is found analytically and thermodynamic quantities are given by simple algebraic functions of these parameters.
• We find that different geometrical properties of the black holes are usefully distinguished by the sum of the black hole and cosmological entropies.