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EMU detection of mysterious multiple component radio-continuum emission from nearby spiral Seyfert I type galaxy ‘Sand-timer’ (NGC 7213)

Year: 2026
Type: article
Abstract: We present an Australian Square Kilometre Array Pathfinder (ASKAP) Evolutionary Map of the Universe (EMU) radio-continuum detection of the nearby spiral Seyfert I type galaxy NGC 7213 which we nickname ‘sand-timer’ due to its morphological appearance. We find an intriguing and peculiar emission extending from the central supermassive black hole (SMBH), which we refer to as galaxy hyperbubbles and/or active galactic nucleus (AGN) jets. Finally, we find two previously undetected kiloparsec-scale features in the polarised intensity image, which appear most likely also related to the central SMBH, as restarted bipolar radio jets, though somewhat obscured in the radio-continuum total intensity image. They resemble the bow shocks often seen in Fanaroff-Riley Class II (FR-II) radio galaxies, and so we propose they most likely represent an early episode of the ‘Sand-timer’s’ AGN jet activity. An alternative scenario is that the core of NGC 7213 may be a super massive binary black hole (SMBBH) which is undergoing a tidal disruption event (TDE), potentially causing the peculiar radio-continuum emission.
DOI: 10.33232/001c.172532
Authors: Miroslav Filipović, Zachary Smeaton, Bärbel Koribalski, Roland Kothes, Adeel Ahmad, Ramy Al Saberi, Crisobal Bordiu, Aaron Bradley, Evan Crawford, Andrew Hopkins, Emilia Jaervelae, Sanja Lazarevic, Denis Leahy, Jeffry Payne, Faisal Rahman, Gavin Rowell, Hidetoshi Sanu, Michael Selby, Stanislav Shabala, Emma Stanton, Sam Taziux, Kisetsu Tsuge, Dejan Urosevic, Nicholas Tothill, Jacco van Loon, Velibor Velovic, Graeme White
Institutions: Western Sydney University, Australia Telescope National Facility, Dominion Astrophysical Observatory, Osservatorio Astrofisico di Catania, National Institute for Astrophysics, Macquarie University, Texas Tech University, University of Calgary, University of Karachi, The University of Adelaide, Gifu University, University of Tasmania, Ruhr University Bochum, University of Belgrade, Keele University
Language: English
Open Access status: diamond
Funders: Science and Industry Endowment Fund, Astronomy Australia Limited, Australian Government, Commonwealth Scientific and Industrial Research Organisation, Curtin University of Technology, Bulgarian Academy of Sciences, Government of Western Australia, Serbian Academy of Sciences and Arts
OpenAlex ID: W7221775554
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