Polarization alignments of radio quasars in JVAS/CLASS surveys

TL;DR

This study investigates the large-scale polarization alignments of radio quasars in the JVAS/CLASS surveys, revealing significant correlations that challenge current explanations and connect to optical polarization phenomena.

Contribution

It provides the first statistical evidence of large-scale polarization alignments of radio quasars and links these to optical polarization alignments in specific sky regions.

Findings

Significant large-scale polarization alignments found among quasars.

Alignments occur in regions previously identified with optical polarization correlations.

The results challenge existing physical or bias explanations for polarization alignments.

Abstract

We test the hypothesis that the polarization vectors of flat-spectrum radio sources (FSRS) in the JVAS/CLASS 8.4-GHz surveys are randomly oriented on the sky. The sample with robust polarization measurements is made of $4155$ objects and redshift information is known for $1531$ of them. We performed two statistical analyses: one in two dimensions and the other in three dimensions when distance is available. We find significant large-scale alignments of polarization vectors for samples containing only quasars (QSO) among the varieties of FSRS's. While these correlations prove difficult to explain either by a physical effect or by biases in the dataset, the fact that the QSO's which have significantly aligned polarization vectors are found in regions of the sky where optical polarization alignments were previously found is striking.