Four Years of Fermi LAT Observations of Narrow-Line Seyfert 1 Galaxies

TL;DR

This study analyzes four years of Fermi LAT data to investigate gamma-ray emissions from radio-loud Narrow-Line Seyfert 1 galaxies, exploring their jet properties and potential as a new class of AGN.

Contribution

It provides the first extensive analysis of gamma-ray emissions from radio-loud NLSy1 galaxies using four years of Fermi LAT data, suggesting they may form a new class of gamma-ray emitting AGN.

Findings

Detection of variable gamma-ray emission from NLSy1s

Comparison of NLSy1 properties with blazar characteristics

Implications for jet formation in spiral-hosted AGN

Abstract

Before the launch of the Fermi satellite only two classes of AGN were known to generate relativistic jets and thus emit up to the gamma-ray energy range: blazars and radio galaxies, both hosted in giant elliptical galaxies. The first two years of observations by the Large Area Telescope (LAT) on board Fermi confirmed that these two are the most numerous classes of identified sources in the extragalactic gamma-ray sky, but the discovery of variable gamma-ray emission from 5 radio-loud Narrow-Line Seyfert 1 galaxies (NLSy1s) revealed the presence of a possible emerging third class of AGN with relativistic jets. Considering also that NLSy1s are typically hosted in spiral galaxy, this finding poses intriguing questions about the nature of these objects, the onset of production of relativistic jets, and the cosmological evolution of radio-loud AGN. Here, we report on a preliminary investigation of the properties of this sample of radio-loud NLSy1 at MeV-GeV photon energies, utilizing the four-year accumulation of Fermi LAT data. In addition we briefly discuss some radio-to-gamma-rays properties of the gamma-ray emitting NLSy1 in the context of the blazar scenario.