Beamed and unbeamed emission of $\gamma$-ray blazars

TL;DR

This paper extends a radio emission model to gamma-ray emission in blazars, showing that gamma-ray output is predominantly from a relativistically beamed component, based on analysis of a large Fermi-LAT blazar sample.

Contribution

It introduces a two-component gamma-ray emission model for blazars, linking radio and gamma-ray beaming factors, and confirms the dominance of beamed gamma-ray emission.

Findings

Gamma-ray emission is mainly from the beamed component.

Correlation between radio and gamma-ray core-dominance parameters established.

Large sample analysis supports the two-component gamma-ray emission model.

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 $\gamma$-ray emission and assume that the total $\gamma$-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 $\gamma$-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 $\gamma$-ray core-dominance parameters with radio core-dominance parameters. The $\gamma$-ray beaming factor is then used to estimate the beamed and unbeamed components. Our analysis confirms that the $\gamma$-ray emission in blazars is mainly from the beamed component.