Physics of Gamma-Ray Bursts Prompt Emission

Figure 17

Time averaged broadband spectra expected following kinetic energy dissipation at various optical depths. For low optical depth, the two low energy bumps are due to synchrotron emission and the original thermal component, and the high energy bumps are due to inverse Compton phenomenon. At high optical depth, , a Wien peak is formed at ~10 keV and is blue-shifted to the MeV range by the bulk Lorentz factor 100 expected in GRBs. In the intermediate regime, , a flat energy spectrum above the thermal peak is obtained by multiple Compton scattering. Figure is taken from Pe’er et al. [399].