Allowed regions of the parameter space β_down-ϵ_CR using different constraints. The allowed parameter space is given by the intersection of the green shaded area (constrained by the measured FWHM) and the hatched region (constrained by the upper limit on the electron temperature). The top and bottom panels refer to h_N = 10% and h_N = 50%, respectively. The values of the parameters are the same as in Fig. 3. In the lower panel the dashed gray region shows the saturation region. The crosses labeled Case A and Case B refer to the cases analyzed in Figs. 5 and 6 (see text for explanation).