The radio-loud narrow-line Seyfert 1 galaxy 1H 0323+342 in a galaxy merger

TL;DR

This study examines the distorted radio structures of the gamma-ray emitting radio-loud NLS1 galaxy 1H 0323+342, providing evidence that galaxy mergers can trigger relativistic jets in low-mass SMBHs, challenging existing paradigms.

Contribution

It offers observational support for the merger hypothesis in radio-loud NLS1s and suggests their evolution involves galaxy interactions and merger-induced jet activity.

Findings

Distorted radio morphology indicates a galaxy merger stage.

Coexistence of active jet and relic structures suggests black hole binary precession.

Radio-loud NLS1s may evolve from radio-quiet NLS1s through mergers.

Abstract

The supermassive black holes (SMBHs) of narrow-line Seyfert 1 galaxies (NLS1s) are at the lowest end of mass function of active galactic nuclei (AGNs) and preferentially reside in late-type host galaxies with pseudobulges, which are thought to be formed by internal secular evolution. On the other hand, the population of radio-loud NLS1s presents a challenge for the relativistic jet paradigm that powerful radio jets are exclusively associated with very high mass SMBHs in elliptical hosts, which are built-up through galaxy mergers. We investigated distorted radio structures associated with the nearest gamma-ray emitting, radio-loud NLS1 1H 0323+342. This provides supporting evidence for the merger hypothesis based on the past optical/near-infrared observations of its host galaxy. The anomalous radio morphology consists of two different structures, the inner curved structure of currently active jet and the outer linear structure of low-brightness relics. Such a coexistence might be indicative of the stage of an established black hole binary with precession before the black holes coalesce in the galaxy merger process. 1H 0323+342 and other radio-loud NLS1s under galaxy interactions may be extreme objects on the evolutionary path from radio-quiet NLS1s to normal Seyfert galaxies with larger SMBHs in classical bulges through mergers and merger-induced jet phases.