Collimated radio and optical emission associated with the Seyfert galaxy Markarian 78

It is well established that the radio structures of Seyfert nuclei show strong evidence for the collimated ejection of relativistic plasma from a compact nucleus. There is now increasing evidence that the ionizing continuum in these objects is anisotropic and that both the relativistic plasma and optical continuum may have a related collimation mechanism. In order to investigate this relationship we have made a detailed study of the radio structure and distribution of ionized gas in the Seyfert galaxy Mkn 78. The structure and velocity field of the ionized gas associated with this galaxy have been investigated using long-slit spectroscopy and narrow-band imaging primarily at [O III] λ5007 A. High-sensitivity images of the radio continuum have been made using the VLA at 2, 6 and 20 cm. (author)