Abstract
Accreting sources such as AGN, X-ray binaries or gamma-ray bursts are knownto be strong, high energy emitters. The hard emission is though to originatefrom plasmas of thermal and/or non-thermal high energy particles. Not only doesthis emission allow to probe the unique properties of the matter in an extremeenvironment, but it also has a crucial backreaction on the energetics and thedynamics of the emitting medium itself. Understanding interactions betweenradiation and matter has become a key issue in the modelling of high energysources. Although most cross sections are well known, they are quite complexand the way all processes couple non-linearly is still an open issue. We present a new code that solves the local, kinetic evolution equations fordistributions of electrons, positrons and photons, interacting by radiationprocesses such as self-absorbed synchrotron and brems-strahlung radiation,Compton scattering, pair production/annihilation, and by Coulomb collisions.The code is very general and aimed to modelled various high energy sources. Asan application, we study the spectral states of X-ray binaries, includingthermalization by Coulomb collisions and synchrotron self-absorption. It isfound that the low-hard and high-soft states can be modelled with differentillumination but the same non-thermal acceleration mechanism.