Discordance of the unified scheme with observed properties of quasars and high-excitation galaxies in the 3CRR sample

TL;DR

This study tests the unified scheme of radio galaxies and quasars using the 3CRR sample, finding discrepancies in size distributions that challenge the model's validity.

Contribution

It provides an updated analysis separating low- and high-excitation galaxies, revealing inconsistencies with the orientation-based unified scheme.

Findings

High-excitation galaxies and quasars roughly match the expected number and luminosity distributions.

No observed size foreshortening of quasars compared to radio galaxies, contrary to model predictions.

Discrepancies suggest the unified scheme may not fully explain the observed properties.

Abstract

We examine the consistency of the unified scheme of FR II-type radio galaxies and quasars with their observed number and size distributions in the 3CRR sample. We separate the low-excitation galaxies from the high-excitation ones, as the former might not harbor a quasar within and thus may not be partaking in the unified scheme models. In the updated 3CRR sample, at low redshifts (z<0.5), the relative number and luminosity distributions of high-excitation galaxies and quasars do roughly match the expectations from the orientation-based unified scheme model. However, a foreshortening in the observed sizes of quasars, a must in the orientation-based model, is not seen with respect to radio galaxies even when the low-excitation galaxies are excluded. This dashes the hope that the unified scheme might still work if one includes only the high-excitation galaxies.