Radio morphology of southern narrow-line Seyfert 1 galaxies with Very Large Array observations

TL;DR

This study uses VLA observations to analyze the radio morphology of southern NLS1 galaxies, revealing diverse emission mechanisms, including jets, outflows, and star formation, and expanding the known sample in the southern hemisphere.

Contribution

It provides new high-resolution radio data for southern NLS1s, identifies kpc-scale jets in some sources, and explores the relationship between radio properties and galaxy features.

Findings

Radio emission mainly concentrated in central regions at kpc-scale

Discovery of new NLS1s with kpc-scale radio jets

Radio-quiet NLS1s show higher luminosity in steep-spectrum sources

Abstract

We present the results of new radio observations carried out with the Karl G. Jansky Very Large Array C-configuration at 5.5 GHz for a sample of southern narrow-line Seyfert 1 galaxies (NLS1s). This work increases the number of known radio-detected NLS1s in the southern hemisphere, and confirms that the radio emission of NLS1s is mainly concentrated in a central region at kpc-scale and only a few sources show diffuse emission. In radio-quiet NLS1s, the radio luminosity tends to be higher in steep-spectrum sources and be lower in flat-spectrum sources, which is opposite to radio-loud NLS1s. This may be because the radio emission of steep NLS1s is dominated by misaligned jets, AGN-driven outflows, or star formation superposing on a compact core. Instead the radio emission of flat NLS1s may be produced by a central core which has not yet developed radio jets and outflows. We discover new NLS1s harboring kpc-scale radio jets and confirm that a powerful jet does not require a large-mass black hole to be generated. We also find sources dominated by star formation. These NLS1s could be new candidates in investigating the radio emission of different mechanisms.