Understanding the Origin of Radio Outflows in Seyfert Galaxies using Radio Polarimetry

TL;DR

This study uses radio polarimetry to investigate the origins of radio outflows in Seyfert galaxies, revealing polarized lobes and structures that help distinguish between AGN-driven and starburst-driven outflows.

Contribution

It provides new polarimetric observations of Seyfert galaxies, identifying unique radio lobe structures and their possible origins, advancing understanding of radio outflows in active galaxies.

Findings

Polarized radio lobes detected in Seyfert galaxies.

NGC 2639 shows highly polarized secondary lobes perpendicular to primary lobes.

Seyfert galaxies exhibit bubble-shaped lobes absent in starburst galaxies.

Abstract

The role of starburst winds versus active galactic nuclei (AGN) jets/winds in the formation of the kiloparsec scale radio emission seen in Seyferts is not yet well understood. In order to be able to disentangle the role of various components, we have observed a sample of Seyfert galaxies exhibiting kpc-scale radio emission suggesting outflows, along with a comparison sample of starburst galaxies, with the EVLA B-array in polarimetric mode at 1.4 GHz and 5~GHz. Polarization is clearly detected in three Seyfert galaxies and one starburst galaxy. The Seyfert galaxy NGC\,2639, shows highly polarized secondary radio lobes, not observed before, which are aligned perpendicular to the known pair of radio lobes. The additional pair of lobes represent an older epoch of emission. A multi-epoch multi-frequency study of the starburst-Seyfert composite galaxy NGC\,3079, reveals that the jet together with the starburst superwind and the galactic magnetic fields might be responsible for the well-known 8-shaped radio lobes observed in this galaxy. We find that many of the Seyfert galaxies in our sample show bubble-shaped lobes, which are absent in the starburst galaxies that do not host an AGN.