A Panchromatic View of Relativistic Jets in Narrow-Line Seyfert 1 Galaxies

Filippo D’Ammando,Josefin Larsson,Monica Orienti,Justin Finke,Marcello Giroletti,Claudia Raiteri

doi:10.3390/galaxies4030011

Abstract

The discovery by the Large Area Telescope on board Fermi of variable γ-ray emission from radio-loud narrow-line Seyfert 1 (NLSy1) galaxies revealed the presence of a possible third class of Active Galactic Nuclei (AGN) with relativistic jets in addition to blazars and radio galaxies. Considering that NLSy1 are usually hosted in spiral galaxies, this finding poses intriguing questions about the nature of these objects and the formation of relativistic jets. We report on a systematic investigation of the γ-ray properties of a sample of radio-loud NLSy1, including the detection of new objects, using 7 years of Fermi-LAT data with the new Pass 8 event-level analysis. In addition we discuss the radio-to-very-high-energy properties of the γ-ray emitting NLSy1, their host galaxy, and black hole mass in the context of the blazar scenario and the unification of relativistic jets at different scales.

Highlights

Since its launch on 11 June 2008, the Fermi Gamma-ray Space Telescope has opened a new era in high-energy astrophysics
Considering that narrow-line Seyfert 1 (NLSy1) are usually hosted in spiral galaxies, their detection in γ-rays poses intriguing questions about the nature of these sources, the production of relativistic jets, and the mechanisms of high-energy emission
Four radio-loud NLSy1 galaxies have been detected at high significance by Fermi-Large Area Telescope (LAT) in the first year of operation (i.e., 1H 0323+342, PMN J0948+0022, PKS 1502+036, and PKS 2004−447) and are included in the First LAT source catalog (1FGL) [11]

Summary

Introduction

Since its launch on 11 June 2008, the Fermi Gamma-ray Space Telescope has opened a new era in high-energy astrophysics. Before the launch of the Fermi satellite only two classes of AGN were known to generate strong relativistic jets, and to emit up to the γ-ray energy range: blazars and radio galaxies, both hosted in giant elliptical galaxies [2]. They exhibit strong X-ray variability, steep X-ray spectra, substantial soft X-ray excess and relatively high luminosity (e.g., [8]) These characteristics seem to point to systems with smaller masses of the central black hole (BH; 106 –108 M ) and higher accretion rates (close to or above the Eddington limit) with respect to blazars and radio galaxies. Considering that NLSy1 are usually hosted in spiral galaxies, their detection in γ-rays poses intriguing questions about the nature of these sources, the production of relativistic jets, and the mechanisms of high-energy emission.

The Fermi-LAT View of NLSy1

Fermi-LAT Data Analysis

X-ray Properties

Infrared-to-UV Properties

Radio Properties

SED Modelling of γ-ray Emitting NLSy1