Wide-field imaging and polarimetry for the biggest and brightest in the 20-GHz southern sky

Abstract

We present the wide-field imaging and polarimetry at ν = 20 GHz of seven of the most extended, bright (Stotal > 0.50 Jy), high-frequency selected radio sources in the southern sky with declinations δ < 30 ◦ . 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 (AT20G) Bright Source Sample (Massardi et al. 2008; Burke-Spolaor et al., in prep). The data is of crucial interest for future CMB missions as a collection of information about candidate calibrator sources. We were 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 (LFI) of the Planck ESA mission due to its high level of integrated polarized flux density (� 0.50±0.06 Jy) on a scale of 10 arcminutes. Six out of the seven sources have a clearly detected compact radio core in our images, with either a null detection or less than 2 percent detection of polarised emission from the nuclei. Most sources with detected jets have magnetic field alignments running in a longitudinal configuration, however PKS 1333-33 exhibits transverse fields and an orthogonal change in field geometry from nucleus to jets.