An off-axis relativistic jet seen in the long lasting delayed radio flare of the TDE AT 2018hyz

Itai Sfaradi*, Paz Beniamini, Assaf Horesh, Tsvi Piran, Joe Bright, Lauren Rhodes, David R.A. Williams, Rob Fender, James K. Leung, Tara Murphy, Dave A. Green

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

The Tidal Disruption Event (TDE) AT 2018hyz exhibited a delayed radio flare almost three years after the stellar disruption. Here, we report new radio observations of the TDE AT 2018hyz with the AMI-LA and ATCA spanning from a month to more than four years after the optical discovery and 200 d since the last reported radio observation. We detected no radio emission from 30-220 d after the optical discovery in our observations at 15.5 GHz down to a 3σ level of <0.14 mJy. The fast-rising, delayed radio flare is observed in our radio data set and continues to rise almost ∼1580 d after the optical discovery. We find that the delayed radio emission, first detected 972 d after optical discovery, evolves as t4.2 ± 0.9, at 15.5 GHz. Here, we present an off-axis jet model that can explain the full set of radio observations. In the context of this model, we require a powerful narrow jet with an isotropic equivalent kinetic energy Ek, iso ∼1055 erg, an opening angle of ∼7°, and a relatively large viewing angle of ∼42°, launched at the time of the stellar disruption. Within our framework, we find that the minimal collimated energy possible for an off-axis jet from AT 2018hyz is Ek ≥ 3 × 1052 erg. Finally, we provide predictions based on our model for the light curve turnover time, and for the proper motion of the radio emitting source.

Original languageAmerican English
Pages (from-to)7672-7680
Number of pages9
JournalMonthly Notices of the Royal Astronomical Society
Volume527
Issue number3
DOIs
StatePublished - 1 Jan 2024

Bibliographical note

Publisher Copyright:
© 2023 The Author(s). Published by Oxford University Press on behalf of Royal Astronomical Society.

Keywords

  • radio continuum: transients
  • transients: tidal disruption events

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