Anisotropic CR diffusion and gamma-ray production close to supernova remnants, with an application to W28

Understand

Cosmic rays that escape their acceleration site interact with the ambient medium and produce gamma rays as the result of inelastic proton-proton collisions.

• The detection of such diffuse emission may reveal the presence of an accelerator of cosmic rays, and also constrain the cosmic ray diffusion coefficient in its vicinity.
• Preliminary results in this direction have been obtained in the last years from studies of the gamma-ray emission from molecular clouds located in the vicinity of supernova remnants, which are the prime candidate for cosmic ray production.
• Hints have been found for a significant suppression of the diffusion coefficient with respect to the average one in the Galaxy.