High-resolution emission-line imaging of Seyfert galaxies. I - Observations. II - Evidence for anisotropic ionizing radiation

Abstract

We report a direct imaging survey, conducted with CCD detectors, of 11 Seyfert galaxies (eight type 2's, three type 1's) in [O III] λλ4959, 5007, Hα + [N II] λλ6548, 6584, and their adjacent continua. A mean seeing of 1.3" (FWHM) has enabled the narrow-line regions of all the galaxies to be spatially resolved. Ten of these galaxies contain "linear" radio continuum sources (i.e., double, triple or jetlike straddling the optical continuum nucleus) on the hundreds of parsecs scale, and their VLA maps have been smoothed to the optical seeing to permit a reliable intercomparison. In all 10 galaxies, the [O III] and radio major axes are aligned to within the errors (typically <= 5^deg^). In addition, there is good agreement between the radio and Hα axes, and the spatial scales of radio and line-emitting gases are very similar. In some cases, the [O III] image shows double structure associated with the outer radio components. The nature of this close connection between relativistic and thermal gases is assessed in the companion paper.