On the Unified Scheme of γ-Ray Emitting Jetted Active Galactic Nuclei

Abstract

The discovery of γ - ray emitting Seyfert galaxies has opened a new unified scheme of active galactic nuclei (AGN) in which jetted Seyfert galaxies are viewed as young counterparts of radio loud AGN. In this paper, we investigate the relationship between gamma-ray (γ - ray) properties of jetted Seyfert galaxies and those of traditionally radio galaxies, radio quasars and BL Lac objects. Results show that jetted Seyfert galaxies appear as low luminosity tail of the radio loud AGNs on the luminosity redshift (L_γ – z) plane, indicating an evolutionary link between them. Nevertheless, narrow-line Seyfert galaxies (NLS1s) do not share similar characteristics with Seyfert galaxies as they possess higher luminosities and redshift than Seyfert galaxies, suggestive that NLS1s are more evolved sources. Analyses of γ – ray and radio core-dominance show that for each subclass of jetted AGN, the beaming angle is wider for radio than for γ - ray emissions. While Seyferts and radio galaxies, on average, have similar low inclination to the line of sight, NLS1 objects have orientations similar to quasars and BL Lacs. There is a significant correlation (r ~ 0.7) between the γ - ray core dominance and γ - ray luminosity. The results are consistent with the revised unification scheme and suggests that NLS1s are highly beamed sources whose parent populations can be found among the regular Seyferts and/or radio galaxies