Large-scale outflows in edge-on Seyfert galaxies. I. Optical emission-line imaging and optical spectroscopy

We have launched a search for large-scale (≳ 1 kpc) minor axis outflows in edge-on Seyfert galaxies in order to assess their frequency of occurrence and to study their properties. Here we present optical continuum and Hα + [N II] line images and/or minor axis long-slit spectra of 22 edge-on Seyfert galaxies. Six of these galaxies show at least one of the following: (i) bi-symmetric Hα halos extending along the minor axis, (ii) bright emission-line complexes at distances ≳4 kpc (in projection) out of the disk, and (iii) double-peaked emission-line profiles from the gas along the minor axis, suggesting that a windblown bubble is present. Our results indicate that ≳1/4 of Seyfert galaxies have good evidence for minor axis galactic outflows. Kinetic luminosities of the galactic outflows in our sample Seyfert galaxies are ∼10⁴⁰-10⁴² ergs s^-1, assuming all the observed minor axis emission is produced by the outflow. These values are, in general, ∼0.1 as large as those well-studied cases of superwinds in starburst galaxies (Heckman, Armus, & Miley 1990). However, far-infrared luminosities of our sample Seyfert galaxies are also ∼0.1 as large. Both starburst-driven superwinds and wide-angled outflows from the active galactic nucleus are possible explanations for the observed large-scale outflows.