A ring accelerator? Unusual jet dynamics in the IceCube candidate PKS 1502+106
Artikel i vetenskaplig tidskrift, 2021

On 2019/07/30.86853 UT, IceCube detected a high-energy astrophysical neutrino candidate. The Flat Spectrum Radio Quasar PKS 1502+106 is located within the 50 per cent uncertainty region of the event. Our analysis of 15 GHz Very Long Baseline Array (VLBA) and astrometric 8 GHz VLBA data, in a time span prior and after the IceCube event, reveals evidence for a radio ring structure that develops with time. Several arc-structures evolve perpendicular to the jet ridge line. We find evidence for precession of a curved jet based on kinematic modelling and a periodicity analysis. An outflowing broad line region (BLR) based on the C IV line emission (Sloan Digital Sky Survey) is found. We attribute the atypical ring to an interaction of the precessing jet with the outflowing material. We discuss our findings in the context of a spine-sheath scenario where the ring reveals the sheath and its interaction with the surroundings (narrow line region, NLR, clouds). We find that the radio emission is correlated with the gamma-ray emission, with radio lagging the gamma-rays. Based on the gamma-ray variability time-scale, we constrain the gamma-ray emission zone to the BLR (30-200 r(g)) and within the jet launching region. We discuss that the outflowing BLR provides the external radiation field for gamma-ray production via external Compton scattering. The neutrino is most likely produced by proton-proton interaction in the blazar zone (beyond the BLR), enabled by episodic encounters of the jet with dense clouds, i.e. some molecular cloud in the NLR.

galaxies: active

galaxies: jets

astroparticle physics

black hole physics

quasars: individual: PKS 1502+106

techniques: interferometric


S. Britzen


C. Fendt


A. Tramacere

Université de Genève

I. N. Pashchenko

Russian Academy of Sciences

Frédéric Jaron

Technische Universität Wien

Chalmers, Rymd-, geo- och miljövetenskap, Onsala rymdobservatorium


R. Panis

Silesian University Opava

L. Petrov

NASA Goddard Space Flight Center

M. F. Aller

University of Michigan

H. D. Aller

University of Michigan

M. Zajacek


Polish Academy of Sciences

Universität zu Köln

L. C. Popovic

Univerzitet u Beogradu

Astronomical Observatory Belgrade

Monthly Notices of the Royal Astronomical Society

0035-8711 (ISSN) 1365-2966 (eISSN)

Vol. 503 3 3145-3178


Acceleratorfysik och instrumentering

Subatomär fysik

Astronomi, astrofysik och kosmologi



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