Distribution of the spectral slope α_{[4.85–10.45]} at higher frequencies among different spectral classes of galaxies. Left: two-point spectral index distribution α_{[4.85–10.45]} for different optical spectral classes of galaxies (SF, composites, Seyferts, and LINERs). The mean and median values are listed in Table 1. Right: fractional distribution of steep, flat, and inverted sources among star-forming, composite, Seyfert, and LINER galaxies.