Figure 9
Results of numerical simulations. (a) Photon energy spectra above 3 MeV for several values of \((\bar{{\mathscr{Z}}},\frac{{W}_{0}}{{\lambda }_{{\rm{L}}}})\). (b) The Doppler-boosted synchrotron factor \({{\mathscr{D}}}_{{\rm{synchro}}.{\rm{rad}}.}\equiv {[{\rm{\Gamma }}(1-\langle \beta \rangle \cos {\rm{\Theta }})]}^{-1}\) (5) once the plasma is transparent to the electromagnetic wave (i.e. t ≥ tbreak), as a function of the plasma velocity \({\langle \beta \rangle }_{t\ge {t}_{{\rm{break}}}}=\,{\rm{\max }}\,\langle \beta \rangle \).
