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Unexpected circular radio objects at high Galactic latitude

Published online by Cambridge University Press:  18 January 2021

Ray P. Norris*
Affiliation:
Western Sydney University, Locked Bag 1797, Penrith, NSW2751, Australia CSIRO Astronomy & Space Science, P.O. Box 76, Epping, NSW1710, Australia
Huib T. Intema
Affiliation:
International Centre for Radio Astronomy Research, Curtin University, GPO Box U1987, Perth, WA6845, Australia Leiden Observatory, Leiden University, PO Box 9513, Leiden, NL-2300RA, The Netherlands
Anna D. Kapińska
Affiliation:
National Radio Astronomy Observatory, PO Box 0, Socorro, NM87801, USA
Bärbel S. Koribalski
Affiliation:
Western Sydney University, Locked Bag 1797, Penrith, NSW2751, Australia CSIRO Astronomy & Space Science, P.O. Box 76, Epping, NSW1710, Australia
Emil Lenc
Affiliation:
CSIRO Astronomy & Space Science, P.O. Box 76, Epping, NSW1710, Australia
L. Rudnick
Affiliation:
University of Minnesota, 100 Church St SE, Minneapolis, MN55455, USA
Rami Z. E. Alsaberi
Affiliation:
Western Sydney University, Locked Bag 1797, Penrith, NSW2751, Australia
Craig Anderson
Affiliation:
National Radio Astronomy Observatory, PO Box 0, Socorro, NM87801, USA
G. E. Anderson
Affiliation:
International Centre for Radio Astronomy Research, Curtin University, GPO Box U1987, Perth, WA6845, Australia
E. Crawford
Affiliation:
Western Sydney University, Locked Bag 1797, Penrith, NSW2751, Australia
Roland Crocker
Affiliation:
Australian National University, Canberra, ACT2600, Australia
Jayanne English
Affiliation:
University of Manitoba, Winnipeg, Manitoba R3T 2N2, Canada
Miroslav D. Filipović
Affiliation:
Western Sydney University, Locked Bag 1797, Penrith, NSW2751, Australia
Tim J. Galvin
Affiliation:
International Centre for Radio Astronomy Research, Curtin University, GPO Box U1987, Perth, WA6845, Australia
Andrew M. Hopkins
Affiliation:
Australian Astronomical Optics, Macquarie University, 105 Delhi Rd, North Ryde, NSW2113, Australia
Natasha Hurley-Walker
Affiliation:
International Centre for Radio Astronomy Research, Curtin University, GPO Box U1987, Perth, WA6845, Australia
Susumu Inoue
Affiliation:
iTHEMS, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
Kieran Luken
Affiliation:
Western Sydney University, Locked Bag 1797, Penrith, NSW2751, Australia CSIRO Astronomy & Space Science, P.O. Box 76, Epping, NSW1710, Australia
Peter J. Macgregor
Affiliation:
Western Sydney University, Locked Bag 1797, Penrith, NSW2751, Australia CSIRO Astronomy & Space Science, P.O. Box 76, Epping, NSW1710, Australia
Pero Manojlović
Affiliation:
Western Sydney University, Locked Bag 1797, Penrith, NSW2751, Australia
Josh Marvil
Affiliation:
National Radio Astronomy Observatory, PO Box 0, Socorro, NM87801, USA
Andrew N. O’Brien
Affiliation:
Western Sydney University, Locked Bag 1797, Penrith, NSW2751, Australia CSIRO Astronomy & Space Science, P.O. Box 76, Epping, NSW1710, Australia Center for Gravitation, Cosmology and Astrophysics, Department of Physics, University of Wisconsin-Milwaukee, PO Box 413, Milwaukee, WI53201, USA
Laurence Park
Affiliation:
Western Sydney University, Locked Bag 1797, Penrith, NSW2751, Australia
Wasim Raja
Affiliation:
CSIRO Astronomy & Space Science, P.O. Box 76, Epping, NSW1710, Australia
Devika Shobhana
Affiliation:
Western Sydney University, Locked Bag 1797, Penrith, NSW2751, Australia
Tiziana Venturi
Affiliation:
Istituto di Radioastronomia, INAF, Via Gobetti 101, Bologna40129, Italy
Jordan D. Collier
Affiliation:
Western Sydney University, Locked Bag 1797, Penrith, NSW2751, Australia The Inter-University Institute for Data Intensive Astronomy (IDIA), Department of Astronomy, University of Cape Town, Private Bag X3, Rondebosch 7701, South Africa
Catherine Hale
Affiliation:
CSIRO Astronomy & Space Science, P.O. Box 76, Epping, NSW1710, Australia
Aidan Hotan
Affiliation:
CSIRO Astronomy & Space Science, P.O. Box 76, Epping, NSW1710, Australia
Vanessa Moss
Affiliation:
CSIRO Astronomy & Space Science, P.O. Box 76, Epping, NSW1710, Australia
Matthew Whiting
Affiliation:
CSIRO Astronomy & Space Science, P.O. Box 76, Epping, NSW1710, Australia
*
Author for correspondence: Ray P. Norris, E-mail: raypnorris@gmail.com

Abstract

We have found a class of circular radio objects in the Evolutionary Map of the Universe Pilot Survey, using the Australian Square Kilometre Array Pathfinder telescope. The objects appear in radio images as circular edge-brightened discs, about one arcmin diameter, that are unlike other objects previously reported in the literature. We explore several possible mechanisms that might cause these objects, but none seems to be a compelling explanation.

Type
Research Article
Copyright
© The Author(s), 2021. Published by Cambridge University Press on behalf of the Astronomical Society of Australia

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