Corrected Hubble residuals as a function of the total host stellar mass, showing the mass step. Markers follow the same color and shape code as in Fig. 6. Top: total host stellar mass distribution per Σ_Hα subgroup. Right: distribution per Σ_Hα subgroup a) and per mode b), as shown in Fig. 8. Horizontal red and gray lines indicate M₁ and M₂ weighted mean values, respectively. Central panel: left and right green horizontal dashed lines indicate the weighted mean of SNe Ia hosted by galaxies more or less massive than log (M/M_⊙) = 10 (vertical gray line). The difference between those two magnitudes defines the “mass step.”