MeerKAT discovery of a MIGHTEE Odd Radio Circle

TL;DR

This paper reports the discovery of a new Odd Radio Circle (ORC) in the MIGHTEE survey data, highlighting its smaller size compared to previous ORCs and suggesting more such structures may be found in deeper radio surveys.

Contribution

The paper presents the first detection of an ORC in the MIGHTEE survey, expanding the known population and providing insights into their sizes and potential prevalence in deep radio observations.

Findings

Discovered a new ORC with a 35" diameter at z=0.196

The ORC is 3-5 times smaller than previously known ORCs

Suggests more ORCs will be found in future deeper surveys

Abstract

We present the discovery of a new Odd Radio Circle (ORC J0219--0505) in 1.2~GHz radio continuum data from the MIGHTEE survey taken with the MeerKAT telescope. The radio-bright host is a massive elliptical galaxy, which shows extended stellar structure, possibly tidal tails or shells, suggesting recent interactions or mergers. The radio ring has a diameter of 35", corresponding to 114~kpc at the host galaxy redshift of $z_{\rm spec} = 0.196$. This MIGHTEE ORC is a factor 3--5 smaller than previous ORCs with central elliptical galaxies. The discovery of this MIGHTEE ORC in a deep but relatively small-area radio survey implies that more ORCs will be found in deeper surveys. While the small numbers currently available are insufficient to estimate the flux density distribution, this is consistent with the simplest hypothesis that ORCs have a flux density distribution similar to that of the general population of extragalactic radio sources.