Studying magnetic fields in several parsec-scale AGN jets using Faraday Rotation

TL;DR

This study uses multi-frequency VLBA radio observations to analyze magnetic field structures in AGN jets, providing evidence for helical magnetic fields through Faraday Rotation gradients.

Contribution

It offers new observational evidence supporting the presence of helical magnetic fields in AGN jets by analyzing Faraday Rotation gradients across the jets.

Findings

Evidence for helical magnetic fields in AGN jets.

Detection of Faraday Rotation gradients across jets.

Supports the helical magnetic field model.

Abstract

We present multi-frequency radio observations from the Very Long Baseline Array (VLBA) of selected AGN that seem to have a B-field structure with a central "spine" of B-field orthogonal to the jet and a longitudinal B-field near one or both edges of the jet. Two explanations for this structure have been discussed in the literature: shocks making the central orthogonal field combined with a jet-medium interaction causing the longitudinal "sheath", or both components produced by a helical jet magnetic field. One way to investigate this structure is to look for gradients in the Faraday Rotation across the jet. We will discuss results for 0333+321, 1150+812 and 2037+511 providing evidence for the latter picture.