A deep radio survey of the AKARI North Ecliptic Pole Field - WSRT 20 cm Radio survey description, observations and data reduction

TL;DR

This paper presents a deep 1.4 GHz radio survey of the AKARI North Ecliptic Pole Field using WSRT, cataloging sources and analyzing their counts to study galaxy populations and evolution.

Contribution

It provides the first detailed radio source catalog for this field, with data reduction and source counts analysis, highlighting an excess of faint sources indicating star-forming galaxies.

Findings

Detected 462 sources with fluxes down to 21 microJy

Observed an excess of faint sources below 1 mJy

Compared source counts with previous surveys showing consistency and differences

Abstract

The Westerbork Radio Synthesis Telescope, WSRT, has been used to make a deep radio survey of an ~ 1.7 sq degree field coinciding with the AKARI North Ecliptic Pole Deep Field. The observations, data reduction and source count analysis are presented, along with a description of the overall scientific objectives. The survey consisted of 10 pointings, mosaiced with enough overlap to maintain a similar sensitivity across the central region that reached as low as 21 microJy per beam at 1.4 GHz. A catalogue containing 462 sources detected with a resolution of 17"x15" is presented. The differential source counts calculated from the WSRT data have been compared with those from the shallow VLA-NEP survey of Kollgaard et al 1994, and show a pronounced excess for sources fainter than ~ 1 mJy, consistent with the presence of a population of star forming galaxies at sub-mJy flux levels. The AKARI North Ecliptic Pole Deep field is the focus of a major observing campaign conducted across the entire spectral region. The combination of these data sets, along with the deep nature of the radio observations will allow unique studies of a large range of topics including the redshift evolution of the luminosity function of radio sources, the clustering environment of radio galaxies, the nature of obscured radio-loud active galactic nuclei, and the radio/far-infrared correlation for distant galaxies. This catalogue provides the basic data set for a future series of paper dealing with source identifications, morphologies, and the associated properties of the identified radio sources.