Fermi LAT Observations of Supernova Remnants Interacting with Molecular Clouds: W41, MSH 17-39, and G337.0-0.1

TL;DR

This paper reports the detection of gamma-ray emissions from three supernova remnants interacting with molecular clouds using Fermi LAT data, supporting the idea that these gamma-rays are produced mainly through hadronic processes.

Contribution

First detection of gamma-ray emission from these specific SNRs interacting with molecular clouds, with modeling favoring hadronic origin of the gamma-rays.

Findings

Gamma-ray emissions detected coincident with W41, MSH 17-39, and G337.0-0.1.

Extended and unresolved gamma-ray sources observed.

Modeling suggests gamma-rays are mainly from hadronic processes.

Abstract

We report the detection of gamma-ray emission coincident with three supernova remnants (SNRs) using data from the Large Area Telescope on board the Fermi Gamma-ray Space Telescope. W41, MSH 17-39, and G337.0-0.1 are SNRs known to be interacting with molecular clouds, as evidenced by observations of hydroxyl (OH) maser emission at 1720 MHz in their directions and other observational information. SNR shocks are expected to be sites of cosmic ray acceleration, and clouds of dense material can provide effective targets for production of gamma-rays from neutral pion-decay. The observations reveal unresolved sources in the direction of G337.0-0.1, and MSH 17-39, and an extended source coincident with W41. We model their broadband emission (radio to gamma-ray) using a simple one-zone model, and after considering scenarios in which the MeV-TeV sources originate from either neutral pion-decay or leptonic emission, we conclude that the gamma-rays are most likely produced through the hadronic channel.