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Mysterious odd radio circle near the large magellanic cloud - an intergalactic supernova remnant?

Van Loon

Mysterious odd radio circle near the large magellanic cloud - an intergalactic supernova remnant? Thumbnail


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Abstract

We report the discovery of J0624–6948, a low-surface brightness radio ring, lying between the Galactic Plane and the large magellanic cloud (LMC). It was first detected at 888 MHz with the Australian Square Kilometre Array Pathfinder (ASKAP), and with a diameter of ~196 arcsec. This source has phenomenological similarities to odd radio circles (ORCs). Significant differences to the known ORCs – a flatter radio spectral index, the lack of a prominent central galaxy as a possible host, and larger apparent size – suggest that J0624–6948 may be a different type of object. We argue that the most plausible explanation for J0624–6948 is an intergalactic supernova remnant due to a star that resided in the LMC outskirts that had undergone a single-degenerate type Ia supernova, and we are seeing its remnant expand into a rarefied, intergalactic environment. We also examine if a massive star or a white dwarf binary ejected from either galaxy could be the supernova progenitor. Finally, we consider several other hypotheses for the nature of the object, including the jets of an active galactic nucleus (30Dor) or the remnant of a nearby stellar super-flare.

Acceptance Date Jan 20, 2022
Publication Date May 1, 2022
Publicly Available Date Mar 28, 2024
Journal Monthly Notices of the Royal Astronomical Society
Print ISSN 0035-8711
Publisher Oxford University Press
Pages 265 - 284
DOI https://doi.org/10.1093/mnras/stac210
Publisher URL https://academic.oup.com/mnras/article-abstract/512/1/265/6522201?redirectedFrom=PDF&casa_token=ylj3IxLIOOgAAAAA:pB_0Vmk4FkGZvaZLw38JZRHP-VC8l6v1rgUOa9eVK0tl2uZowOa5XPBkK2U7f7oz3LHrJcVlbYmJx8k

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