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

Jun Yang (Institutionen för rymd- och geovetenskap, Onsala rymdobservatorium) ; Z. Paragi ; A. J. van der Horst ; L. I. Gurvits ; R. M. Campbell ; D. Giannios ; T. An ; S. Komossa
Monthly notices of the Royal Astronomical Society (0035-8711). Vol. 462 (2016), 1, p. L66-L70.
[Artikel, refereegranskad vetenskaplig]

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 mu as (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.

Nyckelord: galaxies: individual: Swift J1644+5734; galaxies: jets; radio continuum: galaxies



Denna post skapades 2016-10-19. Senast ändrad 2016-11-14.
CPL Pubid: 243709

 

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Projekt

Denna publikation är ett resultat av följande projekt:


NEXPReS- Novel EXplorations Pushing Robust e-VLBI Services (NEXPReS) (EC/FP7/261525)

Advanced Radio Astronomy in Europe (RADIONET3) (EC/FP7/283393)