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Photon acceleration in variable ultra-relativistic outflows and high-energy spectra of Gamma-Ray Bursts

Andrei Gruzinov·Peter Meszaros
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Abstract

MeV seed photons produced in shocks in a variable ultra-relativistic outflow gain energy by the Fermi mechanism, because the photons Compton scatter off relativistically colliding shells. The Fermi-modified high-energy photon spectrum has a non-universal slope and a universal cutoff. A significant increase in the total radiative efficiency is possible. In some gamma ray bursts, most of the power might be emitted at the high-energy cutoff for this mechanism, which would be close to 100 MeV for outflows with a mean bulk Lorentz factor of 100.

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Andrei Gruzinov, Peter Meszaros. 2000-04-25. Photon acceleration in variable ultra-relativistic outflows and high-energy spectra of Gamma-Ray Bursts. https://doi.org/10.1086/312829

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