Extended emission line gas in radio galaxies: PKS 0349-27

PKS 0349-27 is a classical FR II radio galaxy whose active galactic nucleus host has a spectacular, spiral-like structure in its extended emission lin e gas (EELG).(2) We have measured the velocity held in this gas and find th at it splits into two cloud groups separated by radial velocities that at s ome points approach 400 km s(-1). Measurements of the diagnostic emission l ine ratios [O III] 5007/H beta, [S II] 6716+6731/H alpha and [N II] 6583/H alpha in these clouds show no evidence for the type of H II region emission associated with starburst activity in either velocity system. The measured emission Pine ratios are similar to those found in the nuclei of narrow-li ne radio galaxies, but the extended ionization/excitation cannot be produce d by continuum emission from the active nucleus alone. We present arguments that suggest that the velocity disturbances seen in the EELG are most like ly the result of a galaxy-galaxy collision or merger, but we cannot complet ely rule out the possibility that the gas has been disrupted by the passage of a radio jet.