Planck early results XIV: ERCSC validation and extreme radio sources

TL;DR

This paper validates the Planck ERCSC radio source data using ground-based observations and archival data, and explores the spectral energy distributions of extreme radio sources at high frequencies, revealing variability and complex spectral features.

Contribution

It combines Planck ERCSC data with ground-based and archival observations to validate source measurements and analyze the spectral properties of extreme radio sources at high frequencies.

Findings

ERCSC source positions and fluxes are consistent with ground-based data

Spectral energy distributions show complex features and variability

High-frequency observations reveal new insights into extragalactic radio sources

Abstract

Planck's all sky surveys at 30-857 GHz provide an unprecedented opportunity to follow the radio spectra of a large sample of extragalactic sources to frequencies 2-20 times higher than allowed by past, large area, ground-based surveys. We combine the results of the Planck Early Release Compact Source Catalog (ERCSC) with quasi-simultaneous ground-based observations, as well as archival data, at frequencies below or overlapping Planck frequency bands, to validate the astrometry and photometry of the ERCSC radio sources and study the spectral features shown in this new frequency window opened by Planck. The ERCSC source positions and flux density scales are found to be consistent with the ground-based observations. We present and discuss the spectral energy distributions (SEDs) of a sample of "extreme" radio sources to illustrate the richness of the ERCSC for the study of extragalactic radio sources. Variability is found to play a role in the unusual spectral features of some of these sources.