τ_SF as a function of M_dyn for the error function model. Same as Fig. 4, but the results shown by the colour map adopt the variable defined by Eq. (21) and shown by the solid curve in Fig. 5. The best-fit solutions (the yellow ridge line) for different M_dyn can be described by two relations, i.e., the black dotted curve (Eq. (18)) for M_dyn <  10^9.5 M_⊙, and the red dash-dotted curve (Eq. (19)) for M_dyn >  10^9.8 M_⊙.