Help Privacy Policy Disclaimer
  Advanced SearchBrowse




Journal Article

Radiative Signatures of Relativistic Shocks


Kirk,  John G.
Division Prof. Dr. Werner Hofmann, MPI for Nuclear Physics, Max Planck Society;


Reville,  Brian
Division Prof. Dr. Werner Hofmann, MPI for Nuclear Physics, Max Planck Society;

External Resource
No external resources are shared
Fulltext (restricted access)
There are currently no full texts shared for your IP range.
Fulltext (public)
There are no public fulltexts stored in PuRe
Supplementary Material (public)
There is no public supplementary material available

Kirk, J. G., & Reville, B. (2010). Radiative Signatures of Relativistic Shocks. Astrophysical Journal Letters, 710(1), 16-20. doi:10.1088/2041-8205/710/1/L16.

Cite as: https://hdl.handle.net/11858/00-001M-0000-0011-7293-5
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.