Polarimetry of relativistic tidal disruption event Swift J2058+0516

TL;DR

This study measures optical linear polarisation in the jetted tidal disruption event Swift J2058+0516, providing insights into its emission mechanisms and confirming non-thermal emission components similar to previous events.

Contribution

First optical polarimetric measurement of Swift J2058+0516, revealing non-zero polarisation and advancing understanding of jet emission in tidal disruption events.

Findings

Detected ~8% optical linear polarisation in Swift J2058+0516

Confirmed non-thermal emission component in the optical band

Similar polarisation levels to Swift J1644+57

Abstract

A small fraction of candidate tidal disruption events (TDEs) show evidence of powerful relativistic jets, which are particularly pronounced at radio wavelengths, and likely contribute non-thermal emission at a wide range of wavelengths. A non-thermal emission component can be diagnosed using linear polarimetry, even when the total received light is dominated by emission from an accretion disk or disk outflow. In this paper we present Very Large Telescope (VLT) measurements of the linear polarisation of the optical light of jetted TDE Swift J2058+0516. This is the second jetted TDE studied in this manner, after Swift J1644+57. We find evidence of non-zero optical linear polarisation, P_V ~ 8%, a level very similar to the near-infrared polarimetry of Swift J1644+57. These detections provide an independent test of the emission mechanisms of the multiwavelength emission of jetted tidal disruption events.