Résumé
Extreme objects such as X-ray binaries, AGN, or $\gamma$-ray bursters harborhigh energy plasmas whose properties are not well understood yet. Not only arethey responsible of the hard X- and $\gamma$-ray emission we observe but alsothey have a strong influence on the main dynamics and energetics of theseobjects themselves. Here we present a new kinetic code that solves theevolution equations for particles and photons around compact objects. Itproduces spectra that will be compared with observations from Simbol-X toconstrain the radiation and acceleration processes in these objects.