IRX – β_CFUV diagram. IRX values were estimated with CIGALE and β_FUV were fitted on the data directly. They are not model-dependant. The black continuous line corresponds to the original Calzetti law, under the assumption that the underlying dust curve follows the Calzetti et al. (2000) attenuation. The dashed line to the predicted law assumes the SMC extinction law (e.g., Gordon et al. 2003). Both are from McLure et al. (2018). The color of the symbols are related to the axis to the right of the figure, the age of the stellar population. Both results with dust emission, DL2014 and PL+OT_MBB, are presented with different symbols with ALMA upper limits and ALMA detections. In the figures, we also plotted the laws from Schulz et al. (2020) at z = 0.0 (blue continuous line), 4.5 (green dotted line), and 5.5 (red dashed line). A comparison with the IRX – β_FUV plot in Fudamoto et al. (2020) with the same sample suggests that our (especially ALMA-detected) galaxies extend less to very blue β_FUV. This is mainly true for the subsample of galaxies not detected in continuum with ALMA. This is probably due to two effects: first, in Fudamoto et al. (2020), 3σ upper limits are plotted. Another possible effect could be because we used a unique IR composite template in the SED fitting, which reduces the uncertainties on L_dust.