Galactic supernova remnant candidates discovered by THOR

Abstract

Context. There is a considerable deficiency in the number of known supernova remnants (SNRs) in the Galaxy compared to that expected. This deficiency is thought to be caused by a lack of sensitive radio continuum data. Searches for extended low-surface brightness radio sources may find new Galactic SNRs, but confusion with the much larger population of H ii regions makes identifying such features challenging. SNRs can, however, be separated from H ii regions using their significantly lower mid-infrared (MIR) to radio continuum intensity ratios.