The compact radio structure of radio-loud narrow line Seyfert 1 galaxies

TL;DR

This study investigates the compact radio structures of three radio-loud narrow line Seyfert 1 galaxies using VLBA data, revealing diverse jet orientations and properties, and highlighting the role of relativistic beaming in their radio loudness.

Contribution

It provides high-resolution radio observations of three NLS1 galaxies, demonstrating that radio loudness can result from intrinsic properties or jet beaming effects, and characterizes their jet structures.

Findings

RXS J16290+4007 shows unresolved structure with signs of relativistic beaming.

RXS J16333+4718 likely has a relativistic jet with core-jet structure.

B3 1702+457 has a resolved jet and a steep spectrum, indicating intrinsic radio loudness.

Abstract

We present the compact radio structure of three radio-loud narrow line Seyfert 1 galaxies from VLBA archive data at 2.3, 5 and 8.4 GHz. In RXS J16290+4007, the radio structure is mostly unresolved. The combination of compact radio structure, high brightness temperature and inverted spectrum between simultaneous 2.3 and 8.4 GHz, strongly favors jet relativistic beaming. Combining with the VLBI data at 1.6 and 8.4 GHz from literatures, we argued that RXS J16333+4718 may also harbor a relativistic jet, with resolved core-jet structure in 5 GHz. B3 1702+457 is clearly resolved with well defined jet component. The overall radio steep spectrum indicates that B3 1702+457 is likely a source optically defined as NLS1 with radio definition of compact steep spectrum sources. From these three sources, we found that radio loud NLS1s can be either intrinsically radio loud (e.g. B3 1702+457), or apparently radio loud due to jet beaming effect (e.g. RXS J16290+4007 and RXS J16333+4718).