Incongruity of the unified scheme with a 3CRR-like equatorial strong-source sample

TL;DR

This study tests the unified scheme of extragalactic radio sources using the BRL sample and finds significant discrepancies with the expected size and quasar fraction distributions, challenging the scheme's validity.

Contribution

It provides the first comparative analysis of the BRL equatorial sample against the 3CRR sample, revealing inconsistencies with the unified scheme.

Findings

No observed foreshortening of quasar sizes in the BRL sample.

Quasar fraction in the BRL sample differs from unified scheme predictions.

Distribution of radio galaxies and quasars in the BRL sample is different from the 3CRR sample.

Abstract

We examine the consistency of the unified scheme of the powerful extragalactic radio sources with the 408 MHz BRL sample from the equatorial sky region, selected at the same flux-density level as the 3CRR sample. We find that, unlike in the 3CRR sample, a foreshortening in the observed sizes of quasars, expected from the orientation-based unified scheme model, is not seen in the BRL sample, at least in different redshift bins up to z~1. Even the quasar fraction in individual redshift bins up to z~1 does not match with that expected from the unified scheme, where radio galaxies and quasars are supposed to belong to a common parent population at all redshifts. This not only casts strong doubts on the unified scheme, but also throws up an intriguing result that in a sample selected from the equatorial sky region, using almost the same criteria as in the 3CRR sample from the northern hemisphere, the relative distribution of radio galaxies and quasars differs qualitatively from the 3CRR sample.