A panchromatic view of relativistic jets in gamma-ray emitting narrow-line Seyfert 1 galaxies

TL;DR

This paper reviews the multiwavelength properties of gamma-ray emitting narrow-line Seyfert 1 galaxies, highlighting their potential as a new class of AGN with relativistic jets, distinct from traditional blazars and radio galaxies.

Contribution

It provides a comprehensive analysis of the radio to gamma-ray characteristics of gamma-ray NLSy1 galaxies and compares them with blazar properties, suggesting a possible new class of jet-producing AGN.

Findings

Gamma-ray NLSy1 galaxies exhibit relativistic jets similar to blazars.

They are hosted in spiral galaxies, unlike blazars in elliptical galaxies.

These galaxies show variable gamma-ray emission, indicating active jet phenomena.

Abstract

Before the launch of the Fermi satellite only two classes of Active Galactic Nuclei (AGN) were known to generate relativistic jets and thus to emit up to the gamma-ray energy range: blazars and radio galaxies, both hosted in giant elliptical galaxies. The first four years of observations by the Large Area Telescope (LAT) on board Fermi confirmed that these two populations represent the most numerous identified sources in the extragalactic gamma-ray sky, but the discovery of variable gamma-ray emission from 5 radio-loud Narrow-Line Seyfert 1 (NLSy1) galaxies revealed the presence of a possible emerging third class of AGN with relativistic jets. Considering that NLSy1 are thought to be hosted in spiral galaxies, this finding poses intriguing questions about the nature of these objects, the knowledge of the development of relativistic jets, and the evolution of radio-loud AGN. In this context, the study of the radio-loud NLSy1 from radio to gamma-rays has received increasing attention. Here we discuss the radio-to-gamma-rays properties of the gamma-ray emitting NLSy1, also in comparison with the blazar scenario.