Odd Radio Circles and their Environment

Abstract

Odd Radio Circles (ORCs) are unexpected faint circles of diffuse radio emission discovered in recent wide deep radio surveys. They are typically about one arcmin in diameter, and may be spherical shells of synchrotron emission about a million light years in diameter, surrounding galaxies at a redshift of ~0.2-0.6. Here we study the properties and environment of the known ORCs. All three known single ORCs either lie in a significant overdensity or have a close companion. If the ORC is caused by an event in the host galaxy, then the fact that they tend to be in an overdensity, or have a close companion, may indicate that the environment is important in creating the ORC phenomenon, possibly because of an increased ambient density or magnetic field.

Published in Special Issue of Galaxies 9(4), 83: "A New Window on the Radio Emission from Galaxies, Galaxy Clusters and Cosmic Web: Current Status and Perspectives", ed. F. Loi & T. Venturi

References in corpus (2)

• E+A and Companion Galaxies - I : A Catalogue and Statistics
• Possible formation of ring galaxies by torus-shaped magnetic wormholes

Cited by in corpus (4)

• MeerKAT uncovers the physics of an Odd Radio Circle
• Mysterious Odd Radio Circle near the Large Magellanic Cloud -- An Intergalactic Supernova Remnant?
• Discovery of Peculiar Radio Morphologies with ASKAP using Unsupervised Machine Learning
• Odd Radio Circles as supernovae remnants in the intragroup medium