Stress-energy tensor in soluble models of spherically symmetric charged black hole evaporation

We study the decay of a near-extremal black hole in AdS2, related to the near-horizon region of (311)-dimensional Reissner-Nordström spacetime, following Fabbri, Navarro, and Navarro-Salas. Back reaction is included in a semiclassical approximation. Calculations of the stress-energy tensor of matter coupled to the physical spacetime for an affine null observer demonstrate that the black hole evaporation proceeds smoothly and the near-extremal black hole evolves back to an extremal ground state, until this approximation breaks down.