SFR vs. M_∗ distribution for the entire sample of Herschel detected sources (~17 000 sources, gray points) and for the 692 sources with X-ray spectral analysis (X-FIR sample, red circles), divided into the five redshift bins defined in Sect. 2.1. The dashed lines in each panel mark the redshift-dependent MS of Withaker et al. (2012). The average 1σ error bars are shown in the top left as a black cross.