Revised optical classification of a sample of gamma-ray emitting AGN with GTC and VLT

TL;DR

This study reclassifies a sample of gamma-ray emitting AGN using new optical spectra, confirming some as narrow-line Seyfert 1 galaxies and discovering new ones, thereby enhancing understanding of jet-launching in AGN with small black holes.

Contribution

The paper provides new optical classifications for gamma-ray AGN, including the discovery of two new NLS1s, and analyzes their black hole properties, advancing knowledge of AGN jet formation.

Findings

Confirmed 4 NLS1s and discovered 2 new NLS1s among gamma-ray AGN.

Black hole masses range from 10^6.25 to 10^9.32 solar masses.

Eddington ratios span from 0.05 to 2.07.

Abstract

We report the results of the optical follow-up of a sample of $\gamma$-ray-emitting active galactic nuclei (AGN). New high-quality optical spectra were obtained using Gran Telescopio Canarias with Optical System for Imaging and low- Intermediate-Resolution Integrated Spectroscopy and the European Southern Observatory Very Large Telescope Unit Telescope 1 with the FOcal Reducer and low dispersion Spectrograph 2. From the analysis of these spectra, we confirmed the previous classification as narrow-line Seyfert 1 (NLS1) for four objects and discovered two new NLS1s, bringing the total number of optically confirmed $\gamma$-NLS1s to 26. We also identified two ambiguous cases between NLS1 and intermediate Seyfert (IS), three IS, one broad-line Seyfert 1, one Seyfert 2. Based on the new spectra, we calculated black hole masses ranging from $10^{6.25}$ to $10^{9.32}$ $M_\odot$, and Eddington ratios spanning 0.05 to 2.07. This reclassification reinforces the scenario in which AGN with relatively small black hole masses are capable of launching powerful relativistic jets, contributing to our broader understanding of $\gamma$-ray-emitting AGN.