No apparent superluminal motion in the first-known jetted tidal disruption event Swift J1644+5734

J. Yang*, Z. Paragi, A. J. van der Horst, L. I. Gurvits, R. M. Campbell, D. Giannios, T. An, S. Komossa

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

28 Citations (Scopus)

Abstract

The first-known tidal disruption event (TDE) with strong evidence for a relativistic jet - based on extensive multiwavelength campaigns - is Swift J1644+5734. In order to directly measure the apparent speed of the radio jet, we performed very long baseline interferometry (VLBI) observations with the European VLBI network (EVN) at 5 GHz. Our observing strategy was to identify a very nearby and compact radio source with the real-time e-EVN, and then utilize this source as a stationary astrometry reference point in the later five deep EVN observations.With respect to the in-beam source FIRST J1644+5736, we have achieved a statistical astrometric precision about 12 μas (68 per cent confidence level) per epoch. This is one of the best phase-referencing measurements available to date. No proper motion has been detected in the Swift J1644+5734 radio ejecta. We conclude that the apparent average ejection speed between 2012.2 and 2015.2 was less than 0.3c with a confidence level of 99 per cent. This tight limit is direct observational evidence for either a very small viewing angle or a strong jet deceleration due to interactions with a dense circum-nuclear medium, in agreement with some recent theoretical studies.

Original languageEnglish
Pages (from-to)L66-L70
JournalMonthly Notices of the Royal Astronomical Society: Letters
Volume462
Issue number1
DOIs
Publication statusPublished - 11 Oct 2016

Keywords

  • galaxies
  • Individual
  • Jets - radio continuum
  • Swift J1644+5734 - galaxies

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