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The 2009 Fermi Symposium

A Bulk Comptonization Model for the Prompt GRB Emission and its Relation to the Fermi GRB Spectra

Demosthenes Kazanas


We present a model in which the GRB prompt emission at E ~ Epeak is due to bulk Comptonization by the relativistic blast wave motion of either its own synchrotron photons or ambient photons of the stellar configuration that gave birth to the GRB. The bulk Comptonization process in photon-proton collisions with the blast wave protons induces also the production of relativistic electrons of Lorentz factor equal to that of the blast wave. The inverse Compton emission of these electrons produces a power law component that extends to multi-GeV energies in good agreement with the LAT GRB observations.