Surface brightness of the Fe-Kα line measured from the MCs in the CMZ, plotted against their estimated column density, N_HC. The labels indicate the identity of each cloud, while the lines represent model predictions for CR electron densities of 100 and 1000 eV/cm³ (lower and upper lines respectively), for assumed slopes of the electron energy spectrum of p = 2 (dotted lines) or p = 3 (dashed lines). CR contribution band as described in the text.