ThePlanck–ATCA Co-eval Observations project: analysis of radio source properties between 5 and 217 GHz

Abstract

The Planck-ATCA Co-eval Observations (PACO) project has yielded observations of 464 sources with the Australia Telescope Compact Array (ATCA) between 4.5 and 40 GHz. The main purpose of the project was to investigate the spectral properties of mm-selected radio sources at frequencies below and overlapping with the ESA's Planck satellite frequency bands, minimizing the variability effects by observing almost simultaneously with the first two Planck all-sky surveys. In this paper we present the whole catalogue of observations in total intensity. By comparing PACO with the various measures of Planck Catalog of Compact Sources (PCCS) flux densities we found the best consistency with the PCCS "detection pipeline" photometry (DETFLUX) that we used to investigate the spectral properties of sources from 5 to 217 GHz. Of our sources, 91 % have remarkably smooth spectrum, well described by a double power law over the full range. This suggests a single emitting region, at variance with the notion that "flat" spectra result from the superposition of the emissions from different compact regions, self absorbed up to different frequencies. Most of the objects show a spectral steepening above ≃ 30 GHz, consistent with synchrotron emission becoming optically thin. Thus, the classical dichotomy between flat-spectrum/compact and steep-spectrum/extended radio sources, well established at cm wavelengths, breaks down at mm wavelengths. The mm-wave spectra do not show indications of the spectral break expected as the effect of "electron ageing", suggesting young source ages.

Polarimetric multi-frequency observations of a complete sample of radio sources

“…1). Almost all of the spectra follow a double power law model (in agreement with PACO results [5]). However, there are 2 sources in total intensity and other 2 in polarisation which depart from this description.…”

“…The Planck-ATCA Co-Eval Observations (PACO project [4,5]) were carried out with ATCA in the 4.5 − 40 GHz frequency range. It observed 464 AT20G objects in 65 epochs between July 2009 and August 2010.…”

ALMACAL IV: a catalogue of ALMA calibrator continuum observations

“…Examples of SEDs of our sample reconstructed using the collection of photometric data described in Sect. 5: 'NED' from the NASA/IPAC Extragalactic database (https://ned.ipac.caltech.edu/ ); 'AT20G' from Murphy et al (2010); 'PCCS2' from Planck Collaboration XXVI (2016); 'PACO' from Massardi et al (2016); 'GLEAM' from Hurley-Walker et al (2017); 'CRATES' from Healey et al (2007); 'ALMA' are the new observations presented in this paper. The complete SED collection for our sample is available on the website of the Italian ARC (http://arc.ia2.inaf.it).…”

“…The NED data were complemented by cross-matching our catalogue with: the Australia Telescope 20GHz Survey Catalog (AT20G; Murphy et al 2010), the PCCS2 (Planck Collaboration XXVI 2016), the PACO catalogue (Massardi et al 2016), the GaLactic and Extragalactic Allsky MWA survey (GLEAM; Hurley-Walker et al 2017), the CRATES survey (Healey et al 2007).…”

Galaxy Evolution in the Radio Band: The Role of Star-forming Galaxies and Active Galactic Nuclei

“…The associated large-scale jets have been shown to affect the thermodyamics of the surrounding intracluster medium (see reviews by Nulsen 2007 andCavaliere &Lapi 2013) and even to lift huge molecular gas reservoirs possibly promoting star formation (see Russell et al 2017). Flat spectrum RL AGNs are instead characterized by more compact radio emission, typically associated to radiatively efficient, thin disk conditions (see review by Heckman & Best 2014; also Massardi et al 2016). …”