Double-peaked Emission Lines Due to a Radio Outflow in KISSR 1219

Abstract

We present the results from 1.5 and 5 GHz phase-referenced VLBA and 1.5 GHz Karl G. Jansky Very Large Array (VLA) observations of the Seyfert 2 galaxy KISSR 1219, which exhibits double-peaked emission lines in its optical spectrum. The VLA and VLBA data reveal a one-sided core-jet structure at roughly the same position angles, providing evidence of an active galactic nucleus outflow. The absence of dual parsec-scale radio cores puts the binary black-hole picture in doubt for the case of KISSR 1219. The high brightness temperatures of the parsec-scale core and jet components (>106 K) are consistent with this interpretation. Doppler boosting with jet speeds of 0.55c to 0.25c, going from parsec to kiloparsec scales, at a jet inclination 50° can explain the jet one-sidedness in this Seyfert 2 galaxy. A blueshifted broad emission line component in [O III] is also indicative of an outflow in the emission line gas at a velocity of ∼350 km s−1 , while the [O I] doublet lines suggest the presence of shock-heated gas. A detailed line ratio study using the MAPPINGS III code further suggests that a shock+precursor model can explain the line ionization data well. Overall, our data suggest that the radio outflow in KISSR 1219 is pushing the emission line clouds, both ahead of the jet and in a lateral direction, giving rise to the double peak emission line spectra.