4FGL J1844.4–0306: High-energy Emission Likely from the Supernova Remnant G29.37 + 0.1

Abstract

Very-high-energy (VHE) observations have revealed approximately 100 TeV sources in our Galaxy, and a significant fraction of them are under investigation to understand their origin. We report our study of one of them, HESS J1844−030. It is found to be possibly associated with the supernova remnant (SNR) candidate G29.37 + 0.1, and detailed studies of the source region at radio and X-ray frequencies have suggested that this SNR is a composite one, containing a pulsar wind nebula (PWN) powered by a candidate young pulsar. As the GeV source 4FGL J1844.4−0306 is also located in the region with high positional coincidence, we analyze its γ-ray data obtained with the Large Area Telescope on board the Fermi Gamma-ray Space Telescope. We determine the GeV γ-ray emission is extended, described with a log-parabola function. The obtained spectrum can be connected to that of the VHE source HESS J1844−030. Given these properties and those from multifrequency studies, we discuss the origin of the γ-ray emission by considering that the two γ-ray sources are associated. Our modeling indicates that while the TeV part would have either a hadronic (from the SNR) or a leptonic origin (from the putative PWN), the GeV part would arise from a hadronic process. Thus we conclude that 4FGL J1844.4−0306 is likely the GeV counterpart to G29.37 + 0.1.