2024ApJ...963...32C

We present new 1.5-8.5 GHz Very Long Baseline Array (VLBA) observations and 0.32-1.26 GHz Giant Meterwave Radio Telescope (GMRT) observations of J0354-1340, which is the only known radio-quiet (RQ) or radio-intermediate (RI) narrow-line Seyfert 1 galaxy with a 100 kpc, two-sided radio jet. A parsec-scale, one-sided jet in the southeastern direction from the core emission is found in the VLBA observations, while the kiloparsec-scale jet observed with the Karl G. Jansky Very Large Array (VLA) and GMRT is in the south-north direction. Core spectra on parsec and kiloparsec scales are presented in combination with archival VLA Sky Survey observations at 3.0 GHz and VLA C-configuration observations at 5.5 GHz. The parsec-scale emission dominates the kiloparsec-scale emission above ∼5 GHz, and the spectrum is inverted due to synchrotron self-absorption. This indicates a compact synchrotron source with a size of ∼0.04 pc, which is associated with either the jet base or the corona. A subkiloparsec-scale jet, which is unresolved on scales of ∼3″, probably dominates the emission below ∼5 GHz. Future radio observations can explore the jet structure between the parsec and 100 kpc scales, the origin of their direction mismatch, and the parsec-scale jet proper motion. It remains to be explored how common such large-scale jets are in RQ or RI active galactic nuclei.