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Description
The supernova remnants Kes 73 and Kes 79 can deposit a large amount of energy to their surroundings and are potentially responsible for particle acceleration. Using the data taken with the Fermi Large Area Telescope (LAT), we confirmed the presence of extended sources which are spatially associated with these two supernova remnants. Kes 73 shows intense emission from 100 MeV to $>$100 GeV, and its LAT spectrum can be decoupled into two components. According to the young age of the Kes 73 system, the observed $<$10 GeV flux is too high for the supernova remnant to account for, while the supernova remnant is reasonably responsible for the hard spectrum above 10 GeV. In the LAT spectrum of Kes 79, we discovered a genuine turnover (a sharp peak) at a photon energy of $290\pm26$ MeV, above which the spectrum follows a power-law with a photon index of $2.63 \pm 0.05$. This peak is consistent with the scenario of proton-proton collision. The molecular clouds illuminated by hadronic cosmic-rays from Kes 79 is preferably dominating the $\gamma$-rays observed in this field.
