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AT2019azh: an unusually long-lived, radio-bright thermal tidal disruption event

Goodwin, A. J. and van Velzen, S. and Miller-Jones, J. C. A. and Mummery, A. and Bietenholz, M. F. and Wederfoort, A. and Hammerstein, E. and Bonnerot, C. and Hoffmann, J. and Yan, L. (2022) AT2019azh: an unusually long-lived, radio-bright thermal tidal disruption event. Monthly Notices of the Royal Astronomical Society, 511 (4). pp. 5328-5345. ISSN 0035-8711. doi:10.1093/mnras/stac333.

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Tidal disruption events (TDEs) occur when a star is destroyed by a supermassive black hole at the centre of a galaxy, temporarily increasing the accretion rate on to the black hole and producing a bright flare across the electromagnetic spectrum. Radio observations of TDEs trace outflows and jets that may be produced. Radio detections of the outflows from TDEs are uncommon, with only about one-third of TDEs discovered to date having published radio detections. Here, we present over 2 yr of comprehensive, multiradio frequency monitoring observations of the TDE AT2019azh taken with the Very Large Array and MeerKAT radio telescopes from approximately 10 d pre-optical peak to 810 d post-optical peak. AT2019azh shows unusual radio emission for a thermal TDE, as it brightened very slowly over 2 yr, and showed fluctuations in the synchrotron energy index of the optically thin synchrotron emission from 450 d post-disruption. Based on the radio properties, we deduce that the outflow in this event is likely non-relativistic and could be explained by a spherical outflow arising from self-stream intersections or a mildly collimated outflow from accretion on to the supermassive black hole. This data set provides a significant contribution to the observational data base of outflows from TDEs, including the earliest radio detection of a non-relativistic TDE to date, relative to the optical discovery.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper ItemCode
Goodwin, A. J.0000-0003-3441-8299
van Velzen, S.0000-0002-3859-8074
Miller-Jones, J. C. A.0000-0003-3124-2814
Bietenholz, M. F.0000-0002-0592-4152
Hammerstein, E.0000-0002-5698-8703
Bonnerot, C.0000-0001-9970-2843
Yan, L.0000-0003-1710-9339
Additional Information:© 2022 The Author(s). Published by Oxford University Press on behalf of Royal Astronomical Society. This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model ( Accepted 2022 February 2. Received 2022 February 2; in original form 2021 December 17. Published: 12 February 2022. The authors thank K. Alexander for helpful discussions, W. Lu for providing helpful comments on an earlier version of this manuscript, and N. Blagorodnova, S. Kulkarni, A. de Witt, B. Cenko, S. Gezari, R. Fender, P. Woudt, and M. Bottcher for their contributions, as well as the anonymous referee for helpful comments. This work was supported by the Australian government through the Australian Research Council’s Discovery Projects funding scheme (DP200102471). The ZTF forced-photometry service was funded under the Heising-Simons Foundation grant #12540303 (PI: Graham). The MeerKAT telescope is operated by the South African Radio Astronomy Observatory, which is a facility of the National Research Foundation, an agency of the Department of Science and Innovation. This work was carried out in part using facilities and data processing pipelines developed at the Inter-University Institute for Data Intensive Astronomy (IDIA). IDIA is a partnership of the Universities of Cape Town, of the Western Cape and of Pretoria. This project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement number 836751. Data Availability: The spectral fitting and equipartition modelling software written for the purpose of this work is publicly available on Github at The observations presented in Table 1 will be published online in a machine-readable format.
Funding AgencyGrant Number
Australian Research CouncilDP200102471
Heising-Simons Foundation12540303
European Research Council (ERC)836751
Subject Keywords:radio continuum: transients –transients: tidal disruption events
Issue or Number:4
Record Number:CaltechAUTHORS:20220426-98060100
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Official Citation:A J Goodwin, S van Velzen, J C A Miller-Jones, A Mummery, M F Bietenholz, A Wederfoort, E Hammerstein, C Bonnerot, J Hoffmann, L Yan, AT2019azh: an unusually long-lived, radio-bright thermal tidal disruption event, Monthly Notices of the Royal Astronomical Society, Volume 511, Issue 4, April 2022, Pages 5328–5345,
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:114467
Deposited By: Tony Diaz
Deposited On:26 Apr 2022 21:12
Last Modified:26 Apr 2022 21:12

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