A 20 GHz Bright Sample for Delta > 72 deg - II. Multi-frequency Follow-up

TL;DR

This study provides multi-frequency follow-up observations of a bright 20 GHz radio source sample in the Northern Polar Cap, analyzing their spectral properties and source classifications to enhance understanding of high-frequency radio sources.

Contribution

It offers new multi-frequency data and spectral analysis for a bright radio source sample, including optical identifications and redshift information, expanding knowledge of high-frequency radio source populations.

Findings

68% of sources are QSOs

27% are radio galaxies

Spectral properties align with other high-frequency samples

Abstract

We present follow-up observations at 5, 8 and 30 GHz of the K-band Northern Wide Survey (KNoWS) 20 GHz Bright Sample, performed with the 32-m Medicina Radio Telescope and the 32-m Torun Radio Telescope. The KNoWS sources were selected in the Northern Polar Cap (Delta > 72 deg) and have a flux density limit S(20GHz) = 115 mJy. We include NVSS 1.4 GHz measurements to derive the source radio spectra between 1.4 and 30 GHz. Based on optical identifications, 68 per cent of the sources are QSOs, and 27 per cent are radio galaxies. A redshift measurement is available for 58 per cent of the sources. The radio spectral properties of the different source populations are found to be in agreement with those of other high-frequency selected samples.