Magnetic Field in the Lobes of the Seyfert Galaxy NGC 3516: Suggestions of a Helical Field

Abstract We present polarization images from the Karl G. Jansky Very Large Array and the Giant Metrewave Radio Telescope at 5.5 GHz, 10 GHz, and 663 MHz of the changing-look active galactic nuclei, NGC 3516. A transverse gradient in the rotation measure (RM) is detected in the northern and southern kiloparsec-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 NGC 3516. 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 NGC 3516.