Ratio of synchrotron and CRe energies as function of the Mach number for different minimum and maximum energy limits (left). A magnetic field of 1 μG was assumed. The right panel shows the same as the bottom row in Fig. 4, but using as weight both the fresh-injection model (solid lines; ℳ_cr = 2.3 with higher transparency) and the re-acceleration model (dashed lines; s = 3 with higher transparency).