For the 39 He II emitters, comparison between the SFR measured fitting the broad-band SED of galaxies and the luminosity of the He II line. The continuous and dashed lines show a linear best fit (with scatter) to the reliable He II emitters with broad emission (red diamonds). The dotted line is the expected correlation between these two quantities according to the cooling radiation model by Yang et al. (2006). The color code of the symbols is the same as in Fig. 10. The right axis reports the star-formation rate needed to produce this level of He II luminosity (as for Fig. 10), assuming a top-heavy IMF with Salpeter slope extending from 1  M_⊙ to 500  s  M_⊙ and metallicity Z = 0.