Jet collimation in a spiral-hosted AGN: a parabolic jet profile in 0313-192

Abstract

Double-lobed active galactic nuclei (DRAGNs) are typically found in elliptical galaxies, while supermassive black holes (SMBHs) in disk galaxies rarely produce powerful kiloparsec-scale jets. However, the growing number of spiral- and disk-hosted DRAGNs challenges this classical dichotomy. We present a study of the jet collimation profile for one such source, 0313–192, using Very Long Base Line Array and Very Large Array data, tracing the jet morphology across nearly 5 orders of magnitude in scale—from ∼a few pc to ∼100 kpc (projected). We find that the jet exhibits a parabolic expansion up to ∼610 pc (∼7.9 × 106 Schwarzschild radii), followed by a transition to a nearly conical shape, assuming kiloparsec-scale emission primarily originates from the jet rather than the lobe. This structural evolution closely resembles those in active galactic nuclei (AGNs) hosted by elliptical galaxies and provides an explanation for how the jet in this system could extend to large distances by magnetohydrodynamic collimation and acceleration. However, this collimation break occurs beyond the sphere of gravitational influence of the SMBH (∼7.3 × 105 RS), and no extended X-ray halos or dense molecular gas structures are detected to provide the necessary external pressure. Therefore, we suggest that jet confinement in 0313–192 is mediated by contributions from nonthermal components, such as ram and magnetic pressure from magnetized disk winds. These mechanisms may enable jet collimation even in the absence of dense ambient gas. Our results highlight how large-scale jets can arise in disk galaxies under rare conditions and demonstrate the need to broaden studies of AGN jet formation beyond traditional models.