TY - JOUR
T1 - Discovery of odd radio circles and other peculiars in the first year of the emu survey using object detection
AU - Gupta, Nikhel
AU - Norris, Ray P.
AU - Hayder, Zeeshan
AU - Huynh, Minh
AU - Andernach, Heinz
AU - Hopkins, Andrew M.
AU - Shabala, Stanislav
AU - Rudnick, Lawrence
AU - Filipović, Miroslav D.
AU - Koribalski, Bärbel S.
AU - Petersson, Lars
AU - Wang, X. Rosalind
PY - 2025/6/26
Y1 - 2025/6/26
N2 - 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.
AB - 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.
KW - galaxies: active
KW - galaxies: peculiar
KW - Galaxy: evolution
KW - methods: data analysis
KW - radio continuum: galaxies
UR - http://www.scopus.com/inward/record.url?scp=105009849698&partnerID=8YFLogxK
U2 - 10.1017/pasa.2025.10061
DO - 10.1017/pasa.2025.10061
M3 - Article
AN - SCOPUS:105009849698
SN - 1323-3580
VL - 42
JO - Publications of the Astronomical Society of Australia
JF - Publications of the Astronomical Society of Australia
M1 - e097
ER -