Gamma-ray emission revealed at the western edge of SNR G344.7-0.1

We report on the investigation of a very high energy (VHE), Galactic gamma-ray source recently discovered at >50GeV using the Large Area Telescope (LAT) on board the Fermi Gamma-Ray Space Telescope. This object, 2FHL J1703.4-4145, displays a very hard >50GeV spectrum with a photon index ~1.2 in the 2FHL catalog and, as such, is one of the most extreme sources in the 2FHL sub-sample of Galactic objects. A detailed analysis of the available multi-wavelength data shows that this source is located on the western edge of the supernova remnant (SNR) G344.7--0.1, along with extended TeV source, HESS J1702-420. The observations and the spectral energy distribution modeling support a scenario where this gamma-ray source is the byproduct of the interaction between the SNR shock and the dense surrounding medium, with escaping cosmic rays (CRs) diffusing into the dense environment and interacting with a large local cloud, generating the observed TeV emission. If confirmed, an interaction between the SNR CRs and a nearby cloud would make 2FHL J1703.4-4145 another promising candidate for efficient particle acceleration of the 2FHL Galactic sample, following the first candidate from our previous investigation of a likely shock-cloud interaction occurring on the West edge of the Vela SNR.
Comment: 9 pages, 7 figures, Submitted to ApJ June 15, 2020. Accepted for publication Oct 2, 2020