Formation and evaporation of charged black holes

We investigate the dynamical formation and evaporation of a spherically symmetric charged black hole. We study the self-consistent one loop order semiclassical back reaction problem. To this end the mass evaporation is modeled by an expectation value of the stress-energy tensor of a neutral massless scalar field, while the charge is not radiated away. We observe the formation of an initially nonextremal black hole which tends toward the extremal black hole M=Q, emitting a Hawking radiation. If the discharge due to the instability of a vacuum-to-pair creation in strong electric fields also occurs, then the black hole discharges and evaporates simultaneously and decays regularly until the scale where the semiclassical approximation breaks down. We calculate the rates of the mass and the charge loss and estimate the lifetime of the decaying black holes.