Profiles of the comoving nonthermal electron/positron number density ﹩{n}_{{\rm{e}}}^{{\prime} }﹩ (left axis, solid black line) together with the Doppler factor ﹩\delta ({R}^{{\prime} })﹩ (right axis, blue dashed line) as a function of the radius of the emitting region ﹩{R}^{{\prime} }﹩. The dotted black line shows the asymptotic ﹩{R}^{{\prime} -2}﹩ scaling at large radii. The vertical dashed lines mark the transition to the reacceleration phase at ﹩{t}_{{\rm{reacc}}}^{{\prime} }﹩ and the deceleration time ﹩{t}_{{\rm{dec}}}^{{\prime} }﹩. The shaded regions indicate the expansion and resdissipation phases.