Characterization of polarimetric and total intensity behaviour of a complete sample of PACO radio sources in the radio bands

Abstract

We present high sensitivity (${\sigma }_P\simeq 0.6$mJy) polarimetric observations in seven bands, from $2.1$ to $38$GHz, of a complete sample of $104$ compact extragalactic radio sources brighter than $200$mJy at $20$GHz. Polarization measurements in six bands, in the range $5.5-38$GHz, for $53$ of these objects were reported by \citet{Galluzzi2017}. We have added new measurements in the same six bands for another 51 sources and measurements at $2.1$GHz for the full sample of $104$ sources. Also, the previous measurements at $18$, $24$, $33$ and $38$GHz were re-calibrated using the updated model for the flux density absolute calibrator, PKS1934-638, not available for the earlier analysis. The observations, carried out with the Australia Telescope Compact Array (ATCA), achieved a $90\%$ detection rate (at $5\sigma$) in polarization. $89$ of our sources have a counterpart in the $72$ to $231$MHz GLEAM survey \citep{HurleyWalker2017}, providing an unparalleled spectral coverage of $2.7$ decades of frequency for these sources. While the total intensity data from $5.5$ to $38$GHz could be interpreted in terms of single component emission, a joint analysis of more extended total intensity spectra presented here, and of the polarization spectra, reveals that over $90\%$ of our sources show clear indications of at least two emission components. We interpret this as an evidence of recurrent activity. Our high sensitivity polarimetry has allowed a $5\sigma$ detection of the weak circular polarization for $\sim 38\%$ of the dataset, and a deeper estimate of $20$GHz polarization source counts than has been possible so far.

18 pages, 7 figures, accepted in MNRAS

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• Simulated catalogs and maps of radio galaxies at millimeter wavelengths in Websky
• Average fractional polarization of extragalactic sources at Planck frequencies
• ALMA Band 3 polarimetric follow-up of a complete sample of faint PACO sources
• Selecting a complete sample of blazars in sub-millimetre catalogues
• QUIJOTE scientific results -- IX. Radio sources in the QUIJOTE-MFI wide survey maps
• A Bayesian method for point source polarization estimation
• Constraining the polarisation flux density and angle of point sources by training a convolutional neural network
• 28 -- 40 GHz variability and polarimetry of bright compact sources in the QUIJOTE cosmological fields
• Extragalactic astrophysics with next-generation CMB experiments