Galactic Cosmic Rays (GCRs) are widely believed to be accelerated at expanding shock waves of supernova remnants (SNRs) through the diffusive shock acceleration mechanism. It has been recognized that enhanced pion decay gamma-rays expected from SNRs that are interacting with molecular clouds could provide direct evidence of the nuclear component of GCRs accelerated at supernova shocks. The Fermi Large Area Telescope (LAT) has been routinely gathering science data since August 2008, surveying the full sky every three hours leading to the detection of several
supernova remnants (SNRs).
Here I will present results on the Fermi-LAT observations of young SNRs, such as Cassiopeia A, as welll as SNRs interacting with molecular clouds, such as W44. The morphological and spectral analyses of these GeV Galactic sources will be described in detailed, followed by a discussion on the possible origin of the gamma-rays detected by Fermi.
