Beamed and Unbeamed Emission of γ-Ray Blazars

Zhiyuan Pei,Denis Bastieri,Jianghe Yang,Junhui Fan

doi:10.1088/1538-3873/abb78f

Abstract

A two-component model of radio emission has been used to explain some radio observational properties of Active Galactic Nuclei (AGNs) and, in particular, of blazars. In this work, we extend the two-component idea to the γ-ray emission and assume that the total γ-ray output of blazars consists of relativistically beamed and unbeamed components. The basic idea leverages the correlation between the radio core-dominance parameter and the γ-ray beaming factor. To do so, we evaluate this correlation for a large sample of 584 blazars taken from the fourth source catalog of the Fermi Large Area Telescope (Fermi-LAT) and correlated their γ-ray core-dominance parameters with radio core-dominance parameters. The γ-ray beaming factor is then used to estimate the beamed and unbeamed components. Our analysis confirms that the γ-ray emission in blazars is mainly from the beamed component.

Highlights

We extend the two-component idea to the γ-ray emission and assume that the total γ-ray output of blazars consists of relativistically beamed and unbeamed components
We evaluate this correlation for a large sample of 584 blazars taken from the fourth source catalog of the Fermi Large Area Telescope (Fermi-LAT) and correlated their γ-ray core-dominance parameters with radio coredominance parameters
According to the optical emission line features, blazars can be divided into flat spectrum radio quasars (FSRQs) and BL Lacertae objects (BL Lacs), where BL Lacs have weak or no emission lines, while FSRQs show stronger emission lines (EW ≥ 5 ̊A, Stocke et al 1991; Stickel et al 1991; Urry & Padovani 1995) in their optical spectra

Summary

Introduction

The most extreme subclass of AGNs, are characterized by large and rapid variability, apparent superluminal motion in their pc-scale jet, strong polarization, high energy γ-ray emission. All of these properties are affected by relativistic beaming. According to the optical emission line features, blazars can be divided into flat spectrum radio quasars (FSRQs) and BL Lacertae objects (BL Lacs), where BL Lacs have weak or no emission lines (i.e. the equivalent width, EW, of the emission line in rest frame is less than 5 A), while FSRQs show stronger emission lines (EW ≥ 5 ̊A, Stocke et al 1991; Stickel et al 1991; Urry & Padovani 1995) in their optical spectra.

Results

Discussion

Conclusion