Radiative Signatures of Relativistic Shocks

Details Radiative Signatures of Relativistic Shocks Radiative Signatures of Relativistic Shocks

2010-01-05

arxiv.org/abs/1001.0687v1

Astrophysical Journal Letters 710 (2010) L16-L20

Astronomy and Astrophysics

Astrophysics

High Energy Astrophysical Phenomena

5 pages, 1 figure, accepted for publication in ApJ Letters

Scientific paper

(Abbreviated) Particle-in-cell simulations of relativistic, weakly magnetized collisionless shocks show that particles can gain energy by repeatedly crossing the shock front. This requires scattering off self-generated small length-scale magnetic fluctuations. The radiative signature of this first-order Fermi acceleration mechanism is important for models of both the prompt and afterglow emission in gamma-ray bursts and depends on the strength parameter "a" of the fluctuations. For electrons (and positrons), acceleration saturates when the radiative losses produced by the scattering cannot be compensated by the energy gained on crossing the shock. We show that this sets an upper limit on both the electron Lorentz factor and on the energy of the photons radiated during the scattering process. This rules out "jitter" radiation on self-excited fluctuations with a < 1 as a source of gamma-rays, although high-energy photons might still be produced when the jitter photons are upscattered in an analog of the synchrotron self-Compton process. In fluctuations with a > 1, radiation is generated by the standard synchrotron mechanism, and the maximum photon energy rises linearly with a, until saturating at approximately 70 MeV.

Affiliated with

Also associated with

No associations

Rating

Radiative Signatures of Relativistic Shocks does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Radiative Signatures of Relativistic Shocks, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Radiative Signatures of Relativistic Shocks will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-540440