Two new analyses of the neutrino-associated blazar TXS 0506+056 use long-term radio observations to better describe the jet responsible for a 2017 multi-messenger event. In 2017, IceCube reports a high-energy neutrino from the direction of TXS 0506+056 that coincides with a gamma-ray outburst, with an association significance reported at about the 3σ level. A delayed radio flare followed, peaking around 2020 after the neutrino detection.
One study analyzes 15 GHz full-polarization VLBI data from 2009–2025 and finds moderate superluminal motions of roughly (1–2)c, along with two quasi-stationary jet components. It also reports ejection of a new jet component around the time of the 2017 neutrino event. Polarization patterns in stacked images are consistent with a stratified spine–sheath structure: an inner spine with electric-vector position angles (EVPAs) aligned with the jet direction and an outer sheath with EVPAs approximately perpendicular. Variability in intensity and polarization, including linear-polarization flares and EVPA rotations of quasi-stationary components, is interpreted as interaction between jet layers.
The second study reinterprets earlier “too-slow” radio jet results by identifying a faster disturbance with apparent speed about 21±1c, masked by slower, radio-bright features. It models this as an ultra-relativistic spine (Lorentz factor Γ>20) embedded in a slower sheath, linking the spine-driven disturbance to the delayed radio flare and noting a similar pattern in a second neutrino-associated event.
