Scattered radiation from gamma ray bursts in the GeV energy range

摘要

The scattering of GeV gamma rays from GRB (and similar energetic sources) by the molecular cloud is studied. It is shown that at such high energies the Delbrück scattering, the elastic scattering of a photon in the Co Cou- ulo lomb field of a nucleus via a virtual electron pair which is a QED process, has a significant contribution. Since the mb Delbrück scattering cross section has a strong dependence on atomic number, in principle the scattered radiation at such high energies can p probe the presence of heavy elements in GRB atmosphere. The possibility of detection of such robe an effect has been discussed.