A GeV source in the direction of Supernova Remnant CTB 37B

TL;DR

This paper reports the detection of GeV gamma-ray emission from the supernova remnant CTB 37B, suggesting efficient particle acceleration and bridging characteristics between young and old SNRs.

Contribution

First detection of GeV gamma-ray emission from CTB 37B, providing insights into particle acceleration mechanisms in SNRs.

Findings

Gamma-ray spectrum fits a power-law with index 1.89

No significant spatial extension or time variation detected

Multi-wavelength data compatible with leptonic or hadronic models

Abstract

Supernova remnants (SNRs) are the most attractive candidates for the acceleration sites of Galactic cosmic rays. We report the detection of GeV $\gamma$-ray emission with the Pass 8 events recorded by Fermi Large Area Telescope (Fermi-LAT) in the vicinity of the shell type SNR CTB 37B that is likely associated with the TeV $\gamma-$ray source HESS J1713-381. The photon spectrum of CTB 37B is consistent with a power-law with an index of $1.89\pm0.08$ in the energy range of $0.5-500$ GeV, and the measured flux connects smoothly with that of HESS J1713-381 at a few hundred GeV. No significant spatial extension and time variation are detected. The multi-wavelength data can be well fitted with either a leptonic model or a hadronic one. However, parameters of both models suggest more efficient particle acceleration than typical SNRs. Meanwhile, the X-ray and $\gamma$-ray spectral properties of CTB 37B show that it is an interesting source bridging young SNRs dominated by non-thermal emission and old SNRs interacting with molecular clouds.