a) Correlation between the 160 μm and the 850 μm fluxes of the galaxies. A linear regression is overlaid (dashed line). When the galaxies do not possess an observational constraint at 850 μm, the flux value was deduced from the SED model. b) 160 μm/850 μm flux density ratios as a function of metallicity. For convention on colors and symbols, see Fig. 4. Red symbols show the galaxies that present a submm excess and for which a cold dust (10 K) component with an emissivity β = 1 is added.