2015ApJ...813....3A

G73.9+0.9 has been classified as a probable shell-type supernova remnant, though it has also been suggested that it could have a pulsar wind nebula (PWN). Here, a broadband model of the non-thermal emission of G73.9+0.9 from radio to gamma rays is presented. The model includes a new gamma-ray observation obtained by the analysis of seven years of data from the Fermi/LAT telescope. Above 200 MeV, the source is detected with a significance of 13σ and the spectrum of the radiation is best described by a power law with an index of ∼2.5. The leptonic mechanisms are hard to reconcile with the measured radio and gamma-ray spectral energy distribution. A PWN origin for the high-energy emission is also not very likely, due to the lack of detection of pulsars and of X-ray emission in the region, as well as from the shape of the gamma-ray spectrum. Given the possibility that the object is interacting with molecular clouds, a hadronic origin of the high-energy emission is more likely, and the spectral properties of the cosmic rays responsible for this radiation are derived.