Unified model of blazars and radio galaxies: synthesizing observational data with relativistic beaming theory

Abstract

The unified model of jetted active galactic nuclei (AGNs) based on intrinsic properties presumes that the blazar subtypes of BL Lacertae objects (BLs) and flat-spectrum radio quasars (FSRQs) are aligned equivalents of Fanaroff–Riley type I (FR I) and Fanaroff–Riley type II (FR II) radio galaxies (RGs) from where their parent sources are obtained. Using compiled radio, X-ray and \(\gamma \)-ray data of 397 Fermi Large Area Telescope (Fermi-LAT) blazars and 153 non-Fermi detected RGs, we computed the \(\gamma \)-ray core-dominance parameter (R_γ) and \(\gamma \)-ray emission components (beamed and unbeamed) to study the consequences of relativistic beaming and orientation effects on \(\gamma \)-ray properties of radio RGs, BLs and FSRQs. Data analysis shows that the distributions of R_X and R_γ, on average, are consistent with the prediction of the unified scheme in which FSRQs and BLs are strongly beamed and inclined at smaller angles than RGs. Through statistical tests with chance probability, \(p < 0.05\), we find that the distributions of R_X and R_γ for radio galaxies and the blazar subtypes are not significantly different. There is a regular positive trend (\(r > +0.60\)) in the variation of radio core-dominance parameter – X-ray luminosity (\(R - L_{\mathrm{x}}\)) data from radio galaxies to FSRQs through BLs, which suggests that radio galaxies could be relativistically less beamed population of jetted AGNs. The results are consistent with the unified model for radio galaxies and the conventional blazar subtypes.