Fermi LAT Observations of Supernova Remnants Interacting with Molecular Clouds

TL;DR

This paper reports the detection of gamma-ray emissions from four supernova remnants interacting with molecular clouds, supporting the idea that SNR shocks accelerate cosmic rays and produce gamma-rays via pion-decay.

Contribution

First detection of gamma-ray emission from four SNRs interacting with molecular clouds using Fermi LAT data, confirming cosmic ray acceleration and pion-decay gamma-ray production.

Findings

Gamma-ray sources detected with >10 sigma significance

Unresolved sources for G349.7+0.2, CTB 37A, 3C 391

Extended source possibly for G8.7-0.1

Abstract

We report the detection of gamma-ray emission coincident with four supernova remnants (SNRs) using data from the Large Area Telescope on board the Fermi Gamma-ray Space Telescope. G349.7+0.2, CTB 37A, 3C 391 and G8.7-0.1 are supernova remnants known to be interacting with molecular clouds, as evidenced by observations of hydroxyl (OH) maser emission at 1720 MHz in their directions. SNR shocks are expected to be sites of cosmic rays acceleration, and clouds of dense material can provide effective targets for production of gamma-rays from pion-decay. The observations reveal unresolved sources in the direction of G349.7+0.2, CTB 37A and 3C 391, and a possibly extended source coincident with G8.7-0.1, all with significance levels greater than 10 sigma.