Electron energy distribution in the emission region calculated at different times (given in units of the light crossing time, R/c) with the parameters used for model A. The equilibrium distribution comprises a cooled low-energy tail N(γ)∝γ⁻², the high-energy tail (rapidly decreasing as a function of energy) of the thermal Maxwellian (which has the peak at γ ≃ 100), and the high-energy nonthermal power law with slope p + 1 (with p = 2.3 the slope of the injected power law) up to the cutoff at γ_c.