MeV seed photons produced in shocks in a variable ultrarelativistic 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 nonuniversal 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.
|Original language||English (US)|
|Issue number||1 PART 2|
|State||Published - Aug 10 2000|
All Science Journal Classification (ASJC) codes
- Astronomy and Astrophysics
- Space and Planetary Science