Detection of the extended $γ$-ray emission around supernova remnant DA 530 with Fermi-LAT

Abstract: We report the extended GeV $\gamma$-ray emission around the high Galactic latitude supernova remnant (SNR) DA 530 with the PASS 8 data recorded by the Fermi Large Area Telescope (Fermi-LAT). The $\gamma$-ray spectrum in the energy range of 100 MeV - 1 TeV follows a power law model with an index of 2.23. The much more extended $\gamma$-ray emission than the radio shell of DA 530 and the spatial coincidence with the molecular cloud suggest that the $\gamma$-ray emission could be originated from the hadronic process, where the high energy protons are accelerated in and escaped from the shock of DA 530. With a steady-state injection model of protons, the $\gamma$-ray spectrum can be well fitted with the typical Galactic value for diffusion coefficient and the low energy content of the total escaped protons.