Detection of GeV $\gamma$-Ray Emission from supernova remnant SNR G15.9+0.2 with Fermi-LAT

TL;DR

This paper reports the first detection of GeV gamma-ray emission from supernova remnant G15.9+0.2 using Fermi-LAT, analyzing its spectral, spatial, and variability characteristics, and discussing possible emission origins.

Contribution

First detection and characterization of GeV gamma-ray emission from SNR G15.9+0.2, including spectral, spatial, and variability analysis, and exploration of emission mechanisms.

Findings

Gamma-ray emission characterized by a power-law index of 2.94.

Emission spatially extended better than a point source.

Weak variability detected over 12.4 years.

Abstract

We first report GeV $\gamma$-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$0.25 with a 6.47$\sigma$ significance level, and the $\gamma$-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 $\gamma$-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$\sigma$ 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 $\gamma$-ray emission may originate from SNR G15.9+0.2. On this basis, we discussed the probable origins of its $\gamma$-ray radiation from leptonic and hadronic scenarios, respectively.