Radio polarization observations of large supernova remnants at 6cm

TL;DR

This study conducted 6cm polarization observations of 79 supernova remnants, providing new flux density measurements, polarization images, and discovering two new SNRs, thereby enhancing understanding of their spectra and magnetic structures.

Contribution

First polarization images at 6cm for many SNRs, new flux measurements, and discovery of two new large supernova remnants in the Galactic plane.

Findings

Ruled out spectral breaks in several SNRs

Confirmed spectral break of S147

Discovered two new SNRs G178.2-4.2 and G25.1-2.3

Abstract

We have observed 79 supernova remnants (SNRs) with the Urumqi 25m telescope at 6cm during the Sino-German 6cm polarization survey of the Galactic plane. We measured flux densities of SNRs at 6cm, some of which are the first ever measured or the measurements at the highest frequency, so that we can determine or improve spectra of SNRs. Our observations have ruled out spectral breaks or spectral flattening that were suggested for a few SNRs, and confirmed the spectral break of S147. By combining our 6cm maps with 11cm and 21cm maps from the Effelsberg 100 m telescope, we calculated the spectral index maps of several large SNRs. For many remnants we obtained for the first time polarization images, which show the intrinsic magnetic field structures at 6cm. We disapproved three objects as being SNRs, OA184, G192.8-1.1 and G16.8-1.1, which show a thermal spectrum and no polarization. We have discovered two large supernova remnants, G178.2-4.2 and G25.1-2.3., in the survey maps.