Normalized radio spectra for relic B1 (top) and B2+B3 (bottom). Each spectrum corresponds to a region from the spectral index map where α_ref − 0.05 < α_ref < α_ref + 0.05, with α_ref = −0.65, −0.75,..., −1.85 for B1, and α_ref =  −0.75, −0.85,..., −1.65 for B2+B3. The spectra are plotted in log ν − log (νI) space to emphasize the differences between the spectra. First order polynomial fits, done in log (I) − log (ν) space, are shown by the solid lines to emphasize possible deviations from power-law radio spectra. Colors correspond to the different α_ref and go from black, blue, purple, red, to orange.