Left: relation between the dust temperature (T_dust) and the total infrared luminosity (L_IR) for galaxies individually detected with Herschel in the CANDELS fields (colored circles, dark purple to yellow from low to high redshift), from ALESS (orange circles) and the HRS (light blue circles). We overplot the best-fit power law (see text) with a black solid line, as well as the values obtained at z = 1.5 by stacking galaxies in different bins of mass (see Sect. 4.1). Right: same as left, but for the mock CANDELS catalog produced with EGG (defined in Sect. 4.2.2).