Simulating radiation and kinetic processes in relativistic plasmas

¹ Centre d'Étude Spatiale des Rayonnements (OMP-UPS-CNRS), 9 avenue du Colonel Roche, BP 44346, 31028 Toulouse Cedex 4, France e-mail: belmont@cesr.fr
² Laboratoire de Physique Théorique et d'Astroparticules, IN2P3/CNRS, Université Montpellier II, CC 70, place Eugène Bataillon, 34095 Montpellier Cedex 5, France

Received: 15 April 2008
Accepted: 6 August 2008

Abstract

Context. Modelling the emission properties of compact high energy sources such as X-ray binaries, AGN or γ-ray bursts represents a complex problem. Contributions of numerous processes participate non linearly to produce the observed spectra: particle-particle, particle-photon and particle-wave interactions. Numerical simulations have been widely used to address the key properties of the high energy plasmas present in these sources.

Aims. We present a code designed to investigate these questions. It includes most of the relevant processes required to simulate the emission of high energy sources.

Methods. This code solves the time-dependent kinetic equations for homogeneous, isotropic distributions of photons, electrons, and positrons. We do not assume that the distribution has any particular shape. We consider the effects of synchrotron self-absorbed radiation, Compton scattering, pair production/annihilation, e-e and e-p Coulomb collisions, e-p bremsstrahlung radiation and some prescriptions for additional particle heating and acceleration.

Results. We illustrate the code's computational capabilities by presenting comparisons with earlier works and some examples. Previous results are reproduced qualitatively but some differences are often found in the details of the particle distribution. As a first application of the code, we investigate acceleration by second order Fermi-like processes and find that the energy threshold for acceleration has a crucial influence on the particle distribution and the emitted spectrum.