20 cm VLA Radio-Continuum Study of M31 - Images and Point Source Catalogues DR2: Extraction of a supernova remnant sample

TL;DR

This study presents a detailed catalog of 916 radio sources in M31 at 20 cm, analyzes their spectral properties, and identifies a limited number of supernova remnants, enhancing understanding of M31's radio emission features.

Contribution

The paper provides a new, comprehensive radio source catalog for M31 at 20 cm, including spectral index analysis and supernova remnant identification, based on archival VLA data.

Findings

Majority of sources are non-thermal, indicating background objects or SNRs.

Only 13 SNRs or candidates detected within the survey area.

Cross-referencing with other catalogs reveals few multi-frequency SNR counterparts.

Abstract

We present Data Release 2 of the Point Source Catalogue created from a series of previously constructed radio-continuum images of M31 at lambda=20 cm (nu=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 lambda=92 cm, the spectral index of 98 sources has been derived. The majority (73%) of these sources exhibit a spectral index of alpha <-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 object in our images within a 5 arcsec search area. Auxiliary optical, radio and X-ray catalogs were cross referenced highlighting a small population of SNR and SNR candidates common to multi-frequency domains.