Detection of GeV ${\hat{I}}^3$-Ray Emission from supernova remnant SNR G15.9+0.2 with Fermi-LAT

Abstract

We first report GeV ${\hat{I}}^3$-ray emission from supernova remnant (SNR) G15.9+0.2 in this work. The results show that its power-law spectral index is 2.94$\pm$0.25 with a 6.47$\ddot{I}ƒ$ significance level, and the ${\hat{I}}^3$-ray emission can be characterized by a two-dimensional (2D) Gaussian spatial distribution, which has a better improvement than the case of a point source. Moreover, we find that its likely counterparts from the radio, X-ray, and TeV energy bands are well coincident with its spatial location. We suggest that the new ${\hat{I}}^3$-ray emission may originate from SNR G15.9+0.2. Analyzing the variability from 12.4 years of the light curve (LC), we identify that this LC exists weak variability with a 2.69$\ddot{I}ƒ$ variability significance level. We investigated the 2D Gaussian extended region and did not identify certified active galactic nuclei from the region of this SNR; thus, we suggest that the new ${\hat{I}}^3$-ray emission may originate from SNR G15.9+0.2. On this basis, we discussed the probable origins of its ${\hat{I}}^3$-ray radiation from leptonic and hadronic scenarios, respectively.