Large-Scale Outflows in Edge-on Seyfert Galaxies. II. Kiloparsec-Scale Radio Continuum Emission

Abstract

We present deep images of the kpc-scale radio continuum emission in 14 edge-on galaxies (ten Seyfert and four starburst galaxies). Observations were taken with the VLA at 4.9~GHz (6~cm). The Seyfert galaxies were selected from a distance-limited sample of 22 objects (defined in paper~I). The starburst galaxies were selected to be well-matched to the Seyferts in radio power, recessional velocity and inclination angle. All four starburst galaxies have a very bright disk component and one (NGC~3044) has a radio halo that extends several kpc out of the galaxy plane. Six of the ten Seyferts observed have large-scale (radial extent $\gapprox$1 kpc) radio structures extending outward from the nuclear region, indicating that large-scale outflows are quite common in Seyferts. Large-scale radio sources in Seyferts are similar in radio power and radial extent to radio halos in edge-on starburst galaxies, but their morphologies do not resemble spherical halos observed in starburst galaxies. The sources have diffuse morphologies, but, in general, they are oriented at skewed angles with respect to the galaxy minor axes. This result is most easily understood if the outflows are AGN-driven jets that are somehow diverted away from the galaxy disk on scales $\gapprox$1 kpc. Starburst-driven winds, however, cannot be ruled out. More observational work is needed to determine whether massive star formation is present at high enough rates to drive galactic winds out to kpc scales in Seyfert galaxies.