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Peer-reviewedCC BY 4.0The Astrophysical Journal

Radio Emission with Dust: A Bow-shock Interpretation for the TDE Candidate AT 2019avd

  • Shuyuan Wei1
  • Yanan Wang2
  • Guobin Mou3
  • Linhui Wu4
  • Santiago del Palacio5
  • Ranieri D. Baldi6
  • Xiaolong Yang4
  • Yang Huang1,2
6 affiliations
  1. 1University of Chinese Academy of Sciences
  2. 2National Astronomical Observatories
  3. 3Nanjing Normal University
  4. 4Shanghai Astronomical Observatory
  5. 5Chalmers University of Technology
  6. 6INAF—Istituto di Radioastronomia
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Abstract

Forward shocks produced by interactions between a single ejected blob and the circumnuclear medium (CNM) around a supermassive black hole are widely invoked to explain radio emission from tidal disruption events (TDEs). However, recent observational evidence such as rapidly rising radio emission, double-peaked broadband spectral energy distributions, and declining shock energies at late times poses challenges to this picture. Alternative scenarios have therefore been proposed, including bow shocks arising from outflows colliding with dense clouds, the production of new ejecta at late times, and variations in microphysical parameters. To investigate the roles of these factors, we analyze the long-lived radio flare of the TDE candidate AT 2019avd, for which dust has been identified through mid-infrared observations, using a radio dataset spanning more than 5 yr. We find that a bow-shock scenario can account for the majority of the observed radio emission, while a forward shock, or an additional bow shock involving different clouds, may begin to dominate at late times. However, a forward-shock scenario remains viable when allowing for evolving microphysical parameters and more complex CNM structures. We discuss the remaining tensions in both the outflow–CNM and outflow–cloud interaction scenarios.

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Cite

BibTeXRIS
BibTeX
@article{wei2026radio,
  title = {{Radio Emission with Dust: A Bow-shock Interpretation for the TDE Candidate AT 2019avd}},
  author = {Shuyuan Wei and Yanan Wang and Guobin Mou and Linhui Wu and Santiago del Palacio and Ranieri D. Baldi and Xiaolong Yang and Yang Huang},
  journal = {The Astrophysical Journal},
  year = {2026},
  month = oct,
  doi = {10.3847/1538-4357/aea4a8},
  url = {https://iopscience.iop.org/article/10.3847/1538-4357/aea4a8},
  note = {CC BY 4.0},
}
RIS
TY  - JOUR
TI  - Radio Emission with Dust: A Bow-shock Interpretation for the TDE Candidate AT 2019avd
AU  - Shuyuan Wei
AU  - Yanan Wang
AU  - Guobin Mou
AU  - Linhui Wu
AU  - Santiago del Palacio
AU  - Ranieri D. Baldi
AU  - Xiaolong Yang
AU  - Yang Huang
PY  - 2026
DA  - 2026/10/07
JO  - The Astrophysical Journal
DO  - 10.3847/1538-4357/aea4a8
UR  - https://iopscience.iop.org/article/10.3847/1538-4357/aea4a8
AB  - Forward shocks produced by interactions between a single ejected blob and the circumnuclear medium (CNM) around a supermassive black hole are widely invoked to explain radio emission from tidal disruption events (TDEs). However, recent observational evidence such as rapidly rising radio emission, double-peaked broadband spectral energy distributions, and declining shock energies at late times poses challenges to this picture. Alternative scenarios have therefore been proposed, including bow shocks arising from outflows colliding with dense clouds, the production of new ejecta at late times, and variations in microphysical parameters. To investigate the roles of these factors, we analyze the long-lived radio flare of the TDE candidate AT 2019avd, for which dust has been identified through mid-infrared observations, using a radio dataset spanning more than 5 yr. We find that a bow-shock scenario can account for the majority of the observed radio emission, while a forward shock, or an additional bow shock involving different clouds, may begin to dominate at late times. However, a forward-shock scenario remains viable when allowing for evolving microphysical parameters and more complex CNM structures. We discuss the remaining tensions in both the outflow–CNM and outflow–cloud interaction scenarios.
SN  - 0004-637X
SN  - 1538-4357
ER  -