A Candidate Relativistic Tidal Disruption Event at 340 Mpc

Creators: Somalwar, Jean J.; Ravi, Vikram; Dong, Dillon Z.; Chen, Yuyang; Breen, Shari; Chandra, Poonam; Clarke, Tracy; De, Kishalay; Gaensler, B. M.; Hallinan, Gregg; Laha, Sibasish; Law, Casey; Myers, Steven T.; Parsotan, Tyler; Peters, Wendy; Polisensky, Emil

Abstract

We present observations of an extreme radio flare, VT J024345.70-284040.08, hereafter VT J0243, from the nucleus of a galaxy with evidence for historic Seyfert activity at redshift z = 0.074. Between NRAO Very Large Array (VLA) Sky Survey observations in 1993 to VLA Sky Survey observations in 2018, VT J0243 rose from a ∼ GHz radio luminosity of νL_ν ≲ 10³⁸ erg s⁻¹ to νL_ν ∼ 10⁴⁰ erg s⁻¹, and still continues to brighten. The radio spectral energy distribution evolution is consistent with a nascent jet that has slowed over ∼3000 days with an average 0.1 <〈β〉< 0.6. The jet i energetic (~10⁵¹⁻⁵² erg), and had a radius ∼0.7 pc in 2021 December. X-ray observations suggest a persistent or evolving corona, possibly associated with an accretion disk, and IR and optical observations constrain any high-energy counterpart to be sub-Eddington. VT J0243 may be an example of a young, off-axis radio jet from a slowly evolving tidal disruption event. Other more mysterious triggers for the accretion enhancement and jet launching are possible. In either case, VT J0243 is a unique example of a nascent jet, highlighting the unknown connection between supermassive black holes, the properties of their accretion flows, and jet launching.

Additional Information

© 2023. The Author(s). Published by the American Astronomical Society. Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. We would like to thank Amy Lien for her help with the Swift BAT data analysis. Based on observations obtained with XMM-Newton, an ESA science mission with instruments and contributions directly funded by ESA Member States and NASA. The Australia Telescope Compact Array is part of the Australia Telescope National Facility (grid.421683.a), which is funded by the Australian Government for operation as a National Facility managed by CSIRO. We acknowledge the Gomeroi people as the traditional owners of the Observatory site. Basic research in radio astronomy at the Naval Research Laboratory is funded by 6.1 Base funding. This research has made use of MAXI data provided by RIKEN, JAXA, and the MAXI team. The Dunlap Institute is funded through an endowment established by the David Dunlap family and the University of Toronto. B.M.G. acknowledges the support of the Natural Sciences and Engineering Research Council of Canada (NSERC) through grants RGPIN-2015-05948 and RGPIN-2022-03163, and of the Canada Research Chairs program. P.C. acknowledges support of the Department of Atomic Energy, Government of India, under the project No. 12-R&D-TFR-5.02-0700. We thank the staff of the GMRT that made these observations possible. The GMRT is run by the National Centre for Radio Astrophysics of the Tata Institute of Fundamental Research. The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc. We thank the staff of the GMRT that made these observations possible. GMRT is run by the National Centre for Radio Astrophysics of the Tata Institute of Fundamental Research. Some of the data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation. The authors wish to recognize and acknowledge the very significant cultural role and reverence that the summit of Maunakea has always had within the indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain. This work made use of data supplied by the UK Swift Science Data Centre at the University of Leicester. Facilities: Swift(XRT) - Swift Gamma-Ray Burst Mission, Keck I(LRIS) - , Keck II(ESI) - , VLA - , WISE - , XMM-Newton(EPIC) - , GMRT - , VLBA. - Software: Astropy (Robitaille et al. 2013; Astropy Collaboration et al. 2018), Matplotlib (Hunter 2007), NumPy (Oliphant 2006; van der Walt et al. 2011), Pandas (pandas development team 2020; Wes McKinney 2010), SciPy (Virtanen et al. 2020), dynesty (Speagle 2020; Skilling 2004; Higson et al. 2019), emcee (Foreman-Mackey et al. 2013), pybdsf (Mohan & Rafferty 2015).

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