Relation between the spectral index and radio-bright and radio-dim regions. From left to right: (i) spectral index as a function of the ratio between the radio surface brightness and the star formation rate per unit area, the colors correspond to the star formation rate per unit area (red corresponds to high values); (ii) star formation rate per unit area (M_⊙ kpc⁻² yr⁻¹); (iii) star formation rate per unit area (contours) on the ratio between the radio continuum surface brightness (Jy/sr) and the star formation rate per unit area (color); (iv) radio continuum surface brightness (contours) on the radio-dim (red) and radio-bright (blue) regions. The radio continuum contour levels are (1, 2, 4, 6, 8, 10, 20, 30, 40, 50)×200 μJy beam⁻¹. The horizontal lines correspond to a size of 1′.