Top panel: fraction of radio-excess sources as a function of the rest-frame FIR luminosity (42.5–122.5 μm, in units of L_⊙); the fraction decreases with increasing L_FIR, as expected since sources with high L_FIR are more likely to be luminous star-forming galaxies. Bottom panel: rest-frame FIR vs. radio 1.4 GHz luminosity (rest-frame); the radio-excess sources are plotted as red circles and some local well known Compton-thick AGNs (open squares) are shown for comparison (data taken from literature). The black dotted line correspond to ⟨ q_RL⟩ =  −0.38 (average for a sample of RL AGN from Evans et al. 2005); the black solid line correspond to q = 2.21 (average for “radio-normal” sources) and the red dashed line correspond to q = 1.68, our selection limit for radio-excess sources.