Left panel: depletion timescale, t_dep(SF) = M_gas/SFR, as a function of the offset from the main sequence, after normalisation to the mid-line of main sequence at each redshift, by removing the redshift dependences with the fitting functions f₁(z) in Table 3 of Genzel et al. (2015) corresponding to CO data, global distribution. Right panel: depletion timescale as a function of the galaxy stellar mass, after normalisation to the mid-line of main sequence, by removing the specific star formation rate dependence with the fitting function g1(sSFR/sSFR(ms,z,M_∗) in Table 3 of Genzel et al. (2015) for CO data, global distribution. Symbols as in Fig. 1. The black pentagon marks J1148+5251 at z = 6.4. The green triangle marks the QSO XID2028 with a detected ionised wind and measured molecular gas mass (Cresci et al. 2015; Brusa et al. 2015b). The red, dashed lines are the best linear fits to the log–log distributions of 500 CO star-forming galaxies in Genzel et al. (2015).