EMU detection of mysterious multiple component radio-continuum emission from nearby spiral Seyfert I type galaxy ‘Sand-timer’ (NGC 7213)
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.
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Authors: M. D. Filipović, Zachary J. Smeaton, B. S. Koribalski, R. Kothes, A. Ahmad, R. Z. E. Alsaberi, C. Bordiu, A. C. Bradley, E. J. Crawford, A. M. Hopkins, E. Järvelä, S. Lazarević, D. Leahy, J. L. Payne, S. F. ur Rahman, G. P. Rowell, H. Sano, M. Selby, S. Shabala, E. J. Stanton, S. Taziaux, K. Tsuge, D. Urosević, N. F. H. Tothill, J. Th. van Loon, V. Velović, G. L. White
Institutions: The University of Adelaide, University of Calgary, University of Belgrade, Macquarie University, Western Sydney University, Ruhr University Bochum, University of Tasmania, Texas Tech University, Keele University, Gifu University, University of Karachi, National Institute for Astrophysics, Australia Telescope National Facility, Dominion Astrophysical Observatory, Osservatorio Astrofisico di Catania