Evolution of charged evaporating black holes

The evaporative evolution of charged nonrotating black holes is studied by numerically integrating a set of coupled differential equations describing the charge and mass as functions of time. We find that large charged black holes will evolve through a region (in the black-hole configuration space) of positive specific heat, undergoing two phase transitions as they evaporate. The region is approximately bounded by $\frac{3}{4}<{\left(\frac{Q}{M}\right)}^2<1\mathrm{}$ and $M>\mathrm{}2.03\mathrm{}\times {10}^7{M}_{\odot }$. Unlike rotating black holes (which always evolve toward the Schwarzschild limit), sufficiently large charged black holes will initially evolve toward the extreme Reissner-Nordström limit; their lifetime may be many orders of magnitude larger than the lifetime of a Schwarzschild black hole with the same initial mass.