THE EMISSION-LINE JET IN MARKARIAN-6

We present the results of Hubble Space Telescope (HST) and MERLIN observations of the Seyfert 1.5 galaxy Mrk 6. FOC/HST images reveal a jetlike feature in the emission line which extends similar to 0.''5, or 250 pc, from the nucleus. The optical jet is cospatial with the southern radio jet, as revealed by a 6 cm MERLIN image matching the HST angular resolution, and shares with it a similar curved morphology. The emission-line jet shows a low-ionization halo surrounding a higher ionization core. This suggests that the optical jet is generated by the expansion of a halo of hot material around the radio jet. Most of the radio and optical emission originates in the innermost 110 pc, which suggests that radio and optical emission are closely associated on this small scale. These results strongly support the interpretation that the structure of the narrow-line region of Mrk 6, and of Seyfert galaxies with known linear radio sources, is dominated by the interaction between the radio ejecta and the surrounding medium.