Wide-Field Imaging and Polarimetry for the Biggest and Brightest in the 20GHz Southern Sky

TL;DR

This study provides wide-field imaging and polarimetry at 20GHz for seven bright, extended radio sources in the southern sky, aiding calibration efforts for cosmic microwave background missions and expanding the understanding of their polarization properties.

Contribution

It offers new high-frequency polarization data for seven key radio sources, identifying Pictor A as a prime calibrator candidate for the Planck mission.

Findings

Pictor A is a strong extragalactic calibrator candidate.

Most sources have a compact core with low polarized emission.

Jet magnetic fields are mostly longitudinal, with some exceptions.

Abstract

We present wide-field imaging and polarimetry at 20GHz of seven of the most extended, bright (Stot >= 0.50 Jy), high-frequency selected radio sources in the southern sky with declinations < -30 deg. Accompanying the data are brief reviews of the literature for each source, The results presented here aid in the statistical completeness of the Australia Telescope 20GHz Survey's bright source sample. The data are of crucial interest for future cosmic microwave background missions as a collection of information about candidate calibrator sources. We are able to obtain data for seven of the nine sources identified by our selection criteria. We report that Pictor A is thus far the best extragalactic calibrator candidate for the Low Frequency Instrument of the Planck European Space Agency mission due to its high level of integrated polarized flux density (0.50+/-0.06 Jy) on a scale of 10 arcmin. Six of the seven sources have a clearly detected compact radio core, with either a null or less than two percent detection of polarized emission from the nucleus. Most sources with detected jets have magnetic field alignments running in a longitudinal configuration, however PKS1333-33 exhibits transverse fields and an orthogonal change in field geometry from nucleus to jets.