The radio structure of the peculiar narrow-line Seyfert 1 galaxy candidate J1100+4421

TL;DR

This study investigates the radio structure of the peculiar NLS1 galaxy candidate J1100+4421, revealing a compact core with high brightness temperature and a large-scale double-sided radio morphology, suggesting a jet viewed at a moderate angle.

Contribution

First high-resolution VLBI observations of J1100+4421 revealing its core and large-scale radio structure, providing insights into its jet orientation and properties.

Findings

Compact core with brightness temperature > 10^10 K

Jet viewing angle estimated at < 26 degrees

Large-scale radio structure ~150 kpc with double-sided morphology

Abstract

Narrow-line Seyfert 1 galaxies (NLS1) are an intriguing subclass of active galactic nuclei. Their observed properties indicate low central black hole mass and high accretion rate. The extremely radio-loud NLS1 sources often show relativistic beaming and are usually regarded as younger counterparts of blazars. Recently, the object SDSS J110006.07+442144.3 was reported as a candidate NLS1 source. The characteristics of its dramatic optical flare indicated its jet-related origin. The spectral energy distribution of the object was similar to that of the gamma-ray detected radio-loud NLS1, PMN J0948+0022. Our high-resolution European Very Long Baseline Interferometry Network observations at 1.7 and 5 GHz revealed a compact core feature with a brightness temperature of >~ 10^(10) K. Using the lowest brightness temperature value and assuming a moderate Lorentz factor of ~9 the jet viewing angle is <~ 26 deg. Archival Very Large Array data show a large-scale radio structure with a projected linear size of ~150 kpc reminiscent of double-sided morphology.