1202.2821 (P. Veres et al.)

Single- and Two-Component GRB Spectra in the Fermi GBM-LAT Energy Range    [PDF]

P. Veres, P. Mészáros

Most Fermi GRB spectra appear as either a broken power law extending to GeV energies or as a broken power with a separate GeV power law component. Here we show that such spectra can be understood in terms of magnetically dominated relativistic jets where a dissipative photosphere produces the prompt MeV emission, which is extended into the GeV range by inverse Compton scattering in the external shock, with possible contributions from a reverse shock as well. The bulk Lorentz factors required in these models are in the range of 300-600, and the MeV-GeV time delays arise naturally. In some cases an optical flash and a sub-dominant thermal component are also present.

View original: http://arxiv.org/abs/1202.2821