New candidate radio supernova remnants detected in the GLEAM survey over $345^\circ < l < 60^\circ$, $180^\circ < l < 240^\circ$

TL;DR

This paper reports the discovery of 27 new supernova remnants in the GLEAM survey, including the faintest ever detected, revealing a steeper-spectrum population and providing new insights into their properties and distribution.

Contribution

The study introduces a novel spectral fitting method to identify faint SNRs in low-frequency radio data, expanding the known population and characterizing their properties.

Findings

Detected 27 new SNRs, including the faintest known.

Identified a steeper radio spectrum in the new SNRs.

Found that many SNRs are larger and younger than previously known.

Abstract

We have detected 27 new supernova remnants (SNRs) using a new data release of the GLEAM survey from the Murchison Widefield Array (MWA) telescope, including the lowest surface-brightness SNR ever detected, G0.1-9.7. Our method uses spectral fitting to the radio continuum to derive spectral indices for 26/27 candidates, and our low-frequency observations probe a steeper-spectrum population than previously discovered. None of the candidates have coincident Wide-field Infrared Survey Explorer mid-IR emission, further showing that the emission is non-thermal. Using pulsar associations we derive physical properties for six candidate SNRs, finding G0.1-9.7 may be younger than 10kyr. 60% of the candidates subtend areas larger than 0.2deg$^{2}$ on the sky, compared to $<25$% of previously-detected SNRs. We also make the first detection of two SNRs in the Galactic longitude range $220^\circ-240^\circ$.