Supernova remnant candidates discovered by the SARAO MeerKAT Galactic Plane Survey

¹ Department of Physics and Astronomy, West Virginia University, Morgantown, WV 26506, USA
² Adjunct Astronomer at the Green Bank Observatory, PO Box 2, Green Bank, WV 24944, USA
³ Center for Gravitational Waves and Cosmology, West Virginia University, Chestnut Ridge Research Building, Morgantown, WV 26505, USA
⁴ South African Radio Astronomy Observatory, 2 Fir Street, Observatory 7925, South Africa
⁵ SARAO/Hartebeesthoek Radio Astronomy Observatory, PO Box 443, Krugersdorp 1740, South Africa
⁶ Department of Physics and Astronomy, York University, Toronto M3J 1P3, Ontario, Canada
⁷ INAF – Osservatorio Astrofisico di Catania, Via S. Sofia 78, 95123 Catania, Italy
⁸ Department of Mathematical Sciences, University of South Africa, Cnr Christian de Wet Rd and Pioneer Avenue, Florida Park, 1709, Roodepoort, South Africa
⁹ Centre for Space Research, Physics Department, North-West University, Potchefstroom 2520, South Africa
¹⁰ Department of Physics and Astronomy, Faculty of Physical Sciences, University of Nigeria, Carver Building, 1 University Road, Nsukka 410001, Nigeria
¹¹ National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22903, USA
¹² School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, UK
¹³ Department of Physics, Aberystwyth University, Ceredigion, Cymru SY23 3BZ, UK

^★ Corresponding author; loren.dean.anderson@gmail.com

Received: 8 June 2024
Accepted: 20 September 2024

Abstract

Context. Sensitive radio continuum data could bring the number of known supernova remnants (SNRs) in the Galaxy more in line with what is expected. Due to confusion in the Galactic plane, however, faint SNRs can be challenging to distinguish from brighter H II regions and filamentary radio emission.

Aims. We exploited new 1.3 GHz SARAO MeerKAT Galactic Plane Survey (SMGPS) radio continuum data, which cover 251° ≤ ℓ ≤ 358° and 2° ≤ ℓ ≤ 61° at | b | ≤ 1.5°, to search for SNR candidates in the Milky Way disk.

Methods. We also used mid-infrared data from the Spitzer GLIMPSE, Spitzer MIPSGAL, and WISE surveys to help identify SNR candidates. These candidates are sources of extended radio continuum emission that lack mid-infrared counterparts, are not known as H II regions in the WISE Catalog of Galactic H II Regions, and have not been previously identified as SNRs.

Results. We locate 237 new Galactic SNR candidates in the SMGPS data. We also identify and confirm the expected radio morphology for 201 objects classified in the literature as SNRs and 130 previously identified SNR candidates. The known and candidate SNRs have similar spatial distributions and angular sizes.

Conclusions. The SMGPS data allowed us to identify a large population of SNR candidates that can be confirmed as true SNRs using radio polarization measurements or by deriving radio spectral indices. If the 237 candidates are confirmed as true SNRs, it would approximately double the number of known Galactic SNRs in the survey area, alleviating much of the discrepancy between the known and expected populations.