Spectral fits of the three macro-regions identified in Sect. 5.2.1. In each panel the mask used to select the region is shown in black in the bottom-left corner, the white part was excluded from the analysis. A simple power-law fit (black line) is shown together with two fits of the CI and CIOFF models. Red line: fit obtained fixing α_inj to −0.6. Blue line: with α_inj allowed to vary. A CI model with α_inj = −0.6 is in general not able to fit the data. Finally, green lines show the fit of a CIOFF model with α_inj fixed to −0.6. ν_b is in GHz.