Unification of BL Lac objects, FR I and FR II(G) radio galaxies and Doppler factor Estimation for BL Lac Objects

TL;DR

This paper investigates the unification of BL Lac objects with FR I and FR II radio galaxies through statistical tests and proposes a method to estimate Doppler factors for BL Lacs, confirming their relatedness.

Contribution

It provides statistical evidence supporting the unification scheme and introduces a new approach to estimate Doppler factors for BL Lac objects.

Findings

Statistical tests suggest BL Lacs and FR I/II(G) galaxies share the same parent distribution.

Proposed Doppler factor estimation method shows good correlation with existing literature.

Supports the unified model of these radio-loud AGN classes.

Abstract

In this work, we collected a sample of BL Lacs, FR I and FR II(G) radio galaxies with available core and extended emissions from published works to discuss the unified schemes and estimate the Doppler factor for BL Lacs. Wilcoxon rank-sum test and Kolmogorov-Smirnov test both suggest that the probabilities for the distribution of the extended luminosity of BL Lacs and that of FR I and FR II(G) radio galaxies to be from the same parent distribution are $p_{\rm{WRS}}=0.779$ and $p_{\rm{K-S}}=0.326$, suggesting they are unified. Based on this unified schemes, we propose to estimate the Doppler factors for BL Lacs. Comparing the Doppler factor estimated by the fitting/regression method with those for the common sources in the literatures, we found a good linear correlation for common sources.