Evidence for a toroidal magnetic field in the core of 3C 84
Abstract
The spatial scales of relativistic radio jets, probed by relativistic magneto-hydrodynamic jet launching simulations (RMHDs) and by most very-long-baseline interferometry (VLBI) observations differ by an order of magnitude. Bridging the gap between these RMHD simulations and VLBI observations requires selecting nearby active galactic nuclei (AGN), the parsec-scale region of which can be resolved. 3C 84 is a nearby bright AGN fulfilling the necessary requirements: it is launching a powerful, relativistic jet powered by a central supermassive black hole, while also being very bright. Using 22 GHz global VLBI measurements of 3C 84 we aim to study its sub-parsec region in both total intensity and linear polarisation, to explore the properties of this jet, with a linear resolution of parsec. We test different simulation setups by altering the bulk Lorentz factor of the jet, as well as the magnetic field configuration (toroidal, poloidal, helical). We confirm the persistence of a limb brightened structure, which reaches deep into the sub-parsec region. The corresponding electric vector position angles (EVPAs) follow the bulk jet flow inside but tend to be orthogonal to it near the edges. Our state-of-the-art RMHD simulations show that this geometry is consistent with a spine-sheath model, associated with a mildly relativistic flow and a toroidal magnetic field configuration.
Cite
@article{arxiv.2405.00097,
title = {Evidence for a toroidal magnetic field in the core of 3C 84},
author = {G. F. Paraschos and L. C. Debbrecht and J. A. Kramer and E. Traianou and I. Liodakis and T. P. Krichbaum and J. -Y. Kim and M. Janssen and D. G. Nair and T. Savolainen and E. Ros and U. Bach and J. A. Hodgson and M. Lisakov and N. R. MacDonald and J. A. Zensus},
journal= {arXiv preprint arXiv:2405.00097},
year = {2024}
}
Comments
10 pages, 8 figures, accepted for publication in Astronomy and Astrophysics