Competition among the cooling timescales for the two-zone model in Figure 11b, as a function of the electron Lorentz factor γ. The times are in the observer frame; that is, corrected by the corresponding $\frac{1+z}{{\delta }_{\text{D}}}$ with respect to the frames comoving with the two regions. Dashed (dotted) curves refer to the blob (core) region. Blue and red curves indicate the synchrotron and SSC cooling timescales, respectively, whereas the green lines represent the light-crossing times. The orange markers indicate the γ_b values of the EED within the two emission regions (Table 4).