Upper panel: L_{γ,  2 GeV} – SFR observed correlation. The dotted green line corresponds to the best-fit model for all the data points of detected SFGs and the shaded region represents the 68% confidence level band. The dashed pink line and associated shaded region show the best-fit model excluding blue markers. The upper limits obtained in Section 2.1, shown as downward-pointing triangles, are not taken into account in the fit. Lower panel: Residuals to the fit excluding blue markers normalized to their standard deviation. The dashed black lines correspond to 4 standard deviations.