Magnetic field in the Lobes of the Seyfert Galaxy NGC3516: Suggestions of a Helical field

TL;DR

This study uses multi-frequency radio polarization observations to reveal a helical magnetic field structure in the lobes of Seyfert galaxy NGC3516, suggesting a magnetically driven jet and wind outflow influencing the galaxy's core dynamics.

Contribution

It provides the first evidence of a helical magnetic field in the lobes of a Seyfert galaxy through detailed polarization and RM gradient analysis.

Findings

Detection of transverse RM gradients indicating a helical magnetic field.

Observation of circular polarization in the core and jet-knot.

Evidence of jet+wind outflow influencing galaxy dynamics.

Abstract

We present polarization images from the Karl G. Jansky Very Large Array (VLA) and the Giant {Metrewave} Radio Telescope (GMRT) at 5.5, 10 GHz and 663 MHz of the changing-look (CL) AGN, NGC3516. A transverse gradient in the rotation measure (RM) is detected in the northern and southern kpc-scale lobes. Such gradients have typically been suggested to be signatures of a helical magnetic (B-) field. We detect circular polarization in the core and inner jet-knot of this source which is known to host a precessing radio jet interacting with emission-line gas. Soft X-ray emission from the Chandra X-ray Observatory suggests the presence of a hot wind emerging from the nucleus of NGC3516. Taken together with the RM gradient, this presents a picture of jet+wind outflow in this Seyfert galaxy with the B-field confining both the jet and lobe emission. A magnetically driven outflow may in turn cause accretion disk warping and jet precession which is observed in the case of NGC3516.