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

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.