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The growing family of gamma-ray narrow-line Seyfert 1 galaxies

Luigi Foschini

TL;DR

The paper surveys the gamma-ray sky as seen by Fermi/LAT, focusing on jetted AGN beyond blazars and highlighting the growing population of Seyfert-type gamma-ray emitters, including NLS1s and CLAGN. By combining rev4FGL data with MOJAVE radio properties, it reveals that NLS1s lie in the low-luminosity tail of the FSRQ distribution and that CLAGN/AMB objects trace the blazar sequence, while gamma-ray luminosity correlates with radio properties such as $L_{15\,\mathrm{GHz}}$ and $T_{\mathrm{b,max}}$. It shows that not all relativistic jets emit gamma rays at detectable levels, with variability, jet orientation, and the location of the dissipation region playing key roles. The work argues for a temporally aware, physically grounded AGN classification that links high-energy emission to jet dynamics, accretion, and host galaxy context, advocating time-domain, multiwavelength studies to advance jet formation and evolution understanding.

Abstract

The revision of the fourth Fermi Large Area Telescope (LAT) catalog of gamma-ray point sources (rev4FGL) revealed that the gamma-ray sky is populated by emerging populations of jetted active galactic nuclei (AGN) other than blazars and radio galaxies. Narrow-Line Seyfert 1, Seyfert 1, intermediate, and Seyfert 2 galaxies, changing-look AGN, plus a number of ambiguous or unclassified sources. After a short historical introduction on the gamma-ray observations of Seyfert-type AGN, I explore the main statistical properties of 1477 jetted AGN from the rev4FGL with spectroscopic redshift, and also the cross-match with Very Large Baseline Array (VLBA) radio observations at 15~GHz from the Monitoring Of Jets in Active galactic nuclei with VLBA Experiments (MOJAVE) program. I then discuss the difference between gamma and non-gamma jetted AGN, and the implications on the classification.

The growing family of gamma-ray narrow-line Seyfert 1 galaxies

TL;DR

The paper surveys the gamma-ray sky as seen by Fermi/LAT, focusing on jetted AGN beyond blazars and highlighting the growing population of Seyfert-type gamma-ray emitters, including NLS1s and CLAGN. By combining rev4FGL data with MOJAVE radio properties, it reveals that NLS1s lie in the low-luminosity tail of the FSRQ distribution and that CLAGN/AMB objects trace the blazar sequence, while gamma-ray luminosity correlates with radio properties such as and . It shows that not all relativistic jets emit gamma rays at detectable levels, with variability, jet orientation, and the location of the dissipation region playing key roles. The work argues for a temporally aware, physically grounded AGN classification that links high-energy emission to jet dynamics, accretion, and host galaxy context, advocating time-domain, multiwavelength studies to advance jet formation and evolution understanding.

Abstract

The revision of the fourth Fermi Large Area Telescope (LAT) catalog of gamma-ray point sources (rev4FGL) revealed that the gamma-ray sky is populated by emerging populations of jetted active galactic nuclei (AGN) other than blazars and radio galaxies. Narrow-Line Seyfert 1, Seyfert 1, intermediate, and Seyfert 2 galaxies, changing-look AGN, plus a number of ambiguous or unclassified sources. After a short historical introduction on the gamma-ray observations of Seyfert-type AGN, I explore the main statistical properties of 1477 jetted AGN from the rev4FGL with spectroscopic redshift, and also the cross-match with Very Large Baseline Array (VLBA) radio observations at 15~GHz from the Monitoring Of Jets in Active galactic nuclei with VLBA Experiments (MOJAVE) program. I then discuss the difference between gamma and non-gamma jetted AGN, and the implications on the classification.
Paper Structure (7 sections, 12 figures, 1 table)

This paper contains 7 sections, 12 figures, 1 table.

Table of Contents

  1. Introduction
  2. Early gamma-ray observations of Seyfert galaxies
  3. The Fermi/LAT gamma-ray sky
  4. Gamma-ray properties
  5. Cross-match with the MOJAVE radio catalog
  6. Do all relativistic jets emit gamma rays?
  7. Final Remarks

Figures (12)

  • Figure 1: Energy spectrum of the type-1.5 Seyfert NGC 4151 (left panel from PEROTTI1983; center panel from WHITE1980; right panel from BAITY1984).
  • Figure 2: The unified model of AGN outlined by L. Woltjer (from BLANDFORD1990). From the top to the bottom: Optically Violent Variable (OVV), Radio Quasars (RQ), Radio Galaxies (RG), Seyfert 2 galaxies (Sy2), Broad Absorption Lines quasars (BAL), Seyfert 1 galaxies (Sy1), Radio Quiet Quasars (QQ). Interestingly, Woltjer had already noted the phenomenon of the changing-look of AGN in the text accompanying the figure, and cited the cases of NGC $3516$, Fairall $9$, PKS $0521-36$.
  • Figure 3: (Left panel) INTEGRAL/IBIS image of the region around 3EG J$1736-2908$ in the $20-40$ keV energy band, showing the 95% and 99% probability contours of the gamma-ray source superimposed (from DICOCCO2004). The Seyfert 1 galaxy GRS $1734-292$ is the only source detected inside the contours. (Right panel) Very Large Array (VLA) observation at $3.5$ cm ($8.5$ GHz) of GRS $1734-292$, showing the jet-like structure (from MARTI1998).
  • Figure 4: Gamma-ray luminosity vs redshift of the 1477 objects with spectroscopic redshifts.
  • Figure 5: Gamma-ray luminosity vs photon index of the 1477 objects with spectroscopic redshifts.
  • ...and 7 more figures