20 cm VLA radio-continuum study of M31-images and point source catalogues DR2: Extraction of a supernova remnant sample

Abstract

We present Data Release 2 of the Point Source Catalogue created from a series of previously constructed radio-continuum images of M31 at λ=20 cm (v=1.4 GHz) from archived VLA observations. In total, we identify a collection of 916 unique discrete radio sources across the field of M31. Comparing these detected sources to those listed by Gelfand et al. (2004) at λ=92 cm, the spectral index of 98 sources has been derived. The majority (73%) of these sources exhibit a spectral index of α<-0.6, indicating that their emission is predominantly non-thermal in nature, which is typical for background objects and Supernova Remnants (SNRs). Additionally, we investigate the presence of radio counterparts for some 156 SNRs and SNR candidates, finding a total of only 13 of these objects in our images within a 500 search area. Auxiliary optical, radio and X-ray catalogues were cross referenced highlighting a small population of SNRs and SNR candidates common to multi frequency domains.

Keywords

• catalogs
• ISM: supernova remnants
• radio continuum: galaxies
• techniques: image processing