Kinematics of ionized gas associated with the radio nucleus and lobes in the active galaxy IRAS 04210 + 0400

ABSTRACT We have used high resolution longslit spectroscopy to investigate the ionized gasin the active galaxy IRAS 04210+0400 and its association with the radio structure.We suggest that two of the ionized components are associated with the centraldouble radio source and observe that the relative positions of these components varyfor different emission lines. Both results are consistent with the radio componentsrepresenting the working surfaces of a pair of jets emerging from the centre of thegalaxy. In this scenario, the optical emission in the centre arises behind the bowshocksproduced by the jets in the interstellar medium.The emission lines are detected and show a dramatic (≈900 km s −1 ) spreadin velocity at the position of the radio lobe hotspots. We suggest a model whichexplains this phenomenon as the result of a jet head emerging through the boundarybetween the interstellar and intergalactic medium. A similar scenario has previouslybeen suggested as a model to explain wide angle tail radio sources (WAT’s). Based onthis model, we simulate the longslit spectra of these regions and compare the resultswith the observations.Key words: galaxies: active - galaxies: individual: IRAS 04210+0400 - galaxies: jets- galaxies: kinematics and dynamics - galaxies: Seyfert