Likely GeV emission from an old Supernova Remnant: SNR G206.9+2.3

Abstract: A novel $\gamma$-ray supernova remnant (SNR) G206.9+2.3 is first reported in this study. We arrived at this conclusion after analyzing 12.4 years of observation data of the Fermi Large Area Telescope (Fermi-LAT). The photon flux of the remnant was (1.19$\pm$0.59) 10$^{-9}$ cm$^{-2}$ s$^{-1}$, and its power-law spectral index was 2.22$\pm$0.19 in the 0.2-500 GeV energy band. Moreover, we found that the test statistic values of the global fit from the four different energy bands were greater than 9. We identified that this was a real $\gamma$-ray signal. Furthermore, we found that its GeV spatial location was in good agreement with that of its radio band. Its spectral energy distribution and light curve properties were similar to those of SNRs. We suggest that the novel $\gamma$-ray source is a likely counterpart to SNR G206.9+2.3. Consequently, we discuss its likely leptonic or hadronic origin.