Discovery of odd radio circles and other peculiars in the first year of the EMU survey using object detection
Abstract We present a systematic search for Odd Radio Circles (ORCs) and other unusual radio morphologies using data from the first year of the Evolutionary Map of the Universe (EMU) survey. ORCs are rare, enigmatic objects characterised by edge-brightened rings of radio emission, often found in association with distant galaxies. To identify these objects, we employ a hybrid methodology combining supervised object detection techniques and visual inspection of radio source candidates. This approach leads to the discovery of five new ORCs and two additional candidate ORCs, expanding the known population of these objects. In addition to ORCs, we also identify 55 Galaxies with Large-scale Ambient Radio Emission (GLAREs), which feature irregular, rectangular, or circular shapes of diffuse radio emission mostly surrounding central host galaxies. These GLAREs may represent different evolutionary stages of ORCs and studying them could offer valuable insights into their evolutionary processes. We also highlight a subset of Starburst Radio Ring Galaxies, which are star-forming galaxies exhibiting edge-brightened radio rings surrounding their central star-forming regions. We emphasise the importance of multi-wavelength follow-up observations to better understand the physical properties, host galaxy characteristics, and evolutionary pathways of these radio sources.
Authors
- Andrew Hopkins (ORCID: https://orcid.org/0000-0002-6097-2747)
- R. P. Norris (ORCID: https://orcid.org/0000-0002-4597-1906)
- Miroslav D Filipović (ORCID: https://orcid.org/0000-0002-4990-9288)
- H. Andernach (ORCID: https://orcid.org/0000-0003-4873-1681)
- L. Rudnick (ORCID: https://orcid.org/0000-0001-5636-7213)
- Zeeshan Hayder (ORCID: https://orcid.org/0009-0009-7421-0311)
- X. Rosalind Wang (ORCID: https://orcid.org/0000-0001-5454-6197)
- N. Gupta (ORCID: https://orcid.org/0000-0001-7652-9451)
- Stanislav S. Shabala (ORCID: https://orcid.org/0000-0001-5064-0493)
- Lars Petersson (ORCID: https://orcid.org/0000-0002-0103-1904)
- Minh Huynh
- B. Koribalski (ORCID: https://orcid.org/0000-0003-4351-993X)
Institutions
- Commonwealth Scientific and Industrial Research Organisation (AU)
- University of Tasmania (AU)
- Australia Telescope National Facility (AU)
- University of Minnesota (US)
- The University of Western Australia (AU)
- University of Minnesota System (US)
- Astronomical Institute of the Slovak Academy of Sciences (SK)
- Astronomy and Space (AU)
- International Centre for Radio Astronomy Research (AU)
- Data61 (AU)
- Western Sydney University (AU)
- Macquarie University (AU)
Publication Details
- Journal
- Publications of the Astronomical Society of Australia
- Published
- 2025-01-01
- DOI
- https://doi.org/10.1017/pasa.2025.10061
- Citations
- 3
- Primary Topic
- Names, Identity, and Discrimination Research
- Type
- article
- Field-Weighted Citation Impact
- 12.60
Funders
- National Aeronautics and Space Administration
- Science and Industry Endowment Fund
- Australian Government
- Commonwealth Scientific and Industrial Research Organisation
- Universidad de Guanajuato
- Government of Western Australia