Gamma-Ray Emission from Supernova Remnants and Surrounding Molecular   Clouds
  Galactic cosmic rays are believed to be accelerated at supernova remnant shocks. Gamma-ray observations of both supernova remnants and associated molecular clouds have been used in several occasions to test (so far quite successfully) this popular hypothesis. Despite that, a conclusive solution to the problem of cosmic ray origin is still missing, and further observational and theoretical efforts are needed. In this paper, the current status of these investigations is briefly reviewed. 
Stefano Gabici (APC)
astro-ph.HE