The polarization in the JVAS/CLASS flat-spectrum radio sources: II. A search for aligned radio polarizations

TL;DR

This study used large radio surveys to test for large-scale polarization alignments in flat-spectrum radio sources, finding no evidence of such alignments or systematic trends across different sky regions.

Contribution

It provides a comprehensive analysis of polarization angles in radio sources, challenging previous claims of cosmological-scale alignments with new, extensive data.

Findings

No large-scale polarization alignments detected.

Polarization angles tend to be perpendicular to jet directions.

No systematic variation of angle differences across the sky.

Abstract

We have used the very large JVAS/CLASS 8.4-GHz surveys of flat-spectrum radio sources to test the hypothesis that there is a systematic alignment of polarization position angle vectors on cosmological scales of the type claimed by Hutsemekers et al (2005). The polarization position angles of 4290 sources with polarized flux density >=1 mJy have been examined. They do not reveal large-scale alignments either as a whole or when split in half into high-redshift (z >= 1.24) and low-redshift sub-samples. Nor do the radio sources which lie in the specific areas covered by Hutsemekers et al (2005). show any significant effect. We have also looked at the position angles of parsec-scale jets derived from VLBI observations and again find no evidence for systematic alignments. Finally, we have investigated the correlation between the polarization position angle and those of the parsec-scale jets. As expected, we find that there is a tendency for the polarization angles to be perpendicular to the jet angles. However, the difference in jet and polarization position angles does not show any systematic trend in different parts of the sky.