What powers the radio emission in TDE AT2019dsg: A long-lived jet or the disruption itself?

Tatsuya Matsumoto*, Tsvi Piran, Julian H. Krolik

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

16 Scopus citations

Abstract

The tidal disruption event AT2019dsg was observed from radio to X-rays and was possibly accompanied by a high-energy neutrino. Previous interpretations have focused on continued injection by a central engine as the source of energy for radio emission. We show that continuous energy injection is unnecessary; the radio data can be explained by a single ejection of plasma that supplies all the energy needed. To support this assertion, we analyse the synchrotron self-absorbed spectra in terms of the equipartition model. Similar to previous analyses, we find that the energy in the radio-emitting region increases approximately t0.7 and the length-scale of this region grows t at a rate ≃ 0.06, c. This event resembles the earliest stage of a supernova remnant: because the ejected mass is much greater than the shocked external mass, its velocity remains unchanged, while the energy in shocked gas grows with time. The radio-emitting material gains energy from the outflow, not from continuing energy injection by the central object. Although energy injection from an accreting BH cannot be completely excluded, the energy injection rate is very different from the fallback luminosity, and maintaining constant outflow velocity requires fine-tuning, demanding further physical explanation. If the neutrino association is real, the energy injection needed is much greater than for the radio emission, suggesting that the detected neutrino did not arise from the radio-emitting region.

Original languageEnglish
Pages (from-to)5085-5092
Number of pages8
JournalMonthly Notices of the Royal Astronomical Society
Volume511
Issue number4
DOIs
StatePublished - 1 Apr 2022

Bibliographical note

Publisher Copyright:
© 2022 The Author(s) Published by Oxford University Press on behalf of Royal Astronomical Society.

Keywords

  • Neutrinos
  • Radio continuum: transients
  • Transients: tidal disruption events

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