Computing cascade processing in astrophysical environments

ORELLANA, M.; PELLIZZA, L.J.; ROMERO, G.E.

Santiago de Chile

Workshop; Supercomputing techniques in astrophysics: school/workshop on parallel computing in astrophysics; 2010

Pontificia Universidad Catolica de Chile, ESO, Durham U., Heildelberg Center para Latinoamerica

Many sources emitting electromagnetic radiation in the range from MeVs to TeVs have been discovered in recent years. The origin of the high-energy radiation in each system is still under debate, while many models have been proposed, in which relativistic particles accelerated in different environments (jets, pulsar wind shocks, colliding stellar winds) interact with ambient matter, radiation, or magnetic fields to produce the high-energy photons.In many of these astrophysical scenarios the radiative processes occur in conditions where the internal gamma-ray absorption becomes unavoidable. If the photon production and absorption take place in relativistic regimes, the gamma-ray propagation problem cannot be reduced to a simple absorption effect. In these regimes, the secondary electrons and positrons (by-product of the absorption) produce a new generation of high-energy gamma-rays, and these photons in turn interact with the surrounding medium producing new generations of electron-positron pairs, so an electromagnetic (EM) cascade develops. The investigation of the astrophysical nature of gamma-ray sources and the processes responsible for their broad-band emission requires a detailed modeling of their observable spectrum. A thorough modeling should therefore include a following of the EM cascades which can be strongly influenced by the structure of the medium and the presence of magnetic fields. In this contribution I present our ongoing efforts to implement a numerical code for simulating cascade phenomena in a self-consistent way.