Two epochs of VLBI observations of eight KISSR seyfert and LINER galaxies: Suggestions of fast and filamentary outflows

Abstract

We present here the results from a second epoch of phase-referenced VLBA observations of eight Seyfert and LINER galaxies from the KISSR sample. These sources were chosen based on the presence of double peaks or asymmetries in their emission lines as observed in SDSS spectra. Parsec-scale radio emission is detected in seven of the eight sources in the second epoch. Jet-like features appear to persist over a ∼4–9 yr timeline in these “radioquiet” AGN. A few sources like KISSR1494, however, show significantly different structures after a 9 yr interval. KISSR102, which was previously suggested to be a binary black hole candidate based on the presence of two compact cores, shows the tentative signatures of superluminal jet motion (1.05 ± 0.45c). Tentative superluminal motion in a jet knot has been reported in another source, KISSR872 (1.65 ± 0.57c). We present 1.5 GHz images from the VLA A-array of four sources. These images reveal core-lobe or core-halo structures. The alignment of the VLBI jet direction with the kiloparsec-scale spectral index gradient, as well as the mismatch between the star formation rate derived from the radio and Hα line emission, support the suggestion that the kiloparsec-scale emission is AGN-jet-related. The jets in KISSR sources appear to lose collimation over spatial scales between 200 pc and 1 kpc. Overall, the characteristics of the KISSR jets are reminiscent of similar properties observed in VLBI monitoring studies of “radio-loud” AGN jets even as subtle differences related to the compactness and brightness of jet features remain.