Number counts of SF sources detected in the VLA- and C-COSMOS surveys, compared to the CDFS determinations. Dotted red histogram: VLA+C-COSMOS class-1 SF candidates. Solid red histogram, with grey error area: VLA+C-COSMOS class-1, 2 SF candidates. Dotted black histogram: C-COSMOS class-1 SF candidates (not requiring radio detection). Solid black histogram: C-COSMOS class-1, 2 SF candidates (not requiring radio detection). Green histogram: galaxy candidates in the CDFS (Xue et al. 2011); their selection criteria are similar to ours for the dotted red histogram. The thick yellow line and the horn-shaped symbol refer to the total (AGN+SF) number counts and fluctuations in the Chandra Deep Fields (Moretti et al. 2003; Miyaji & Griffiths 2002a,b).