Deep 3 GHz Observations of the Lockman Hole North with the Very Large Array -2. Catalogue and \mu Jy source properties

TL;DR

This paper presents deep 3 GHz VLA observations of the Lockman Hole North, resulting in a detailed source catalogue, spectral index analysis, and multi-wavelength classification of radio sources, including AGN and star-forming galaxies.

Contribution

It provides a comprehensive source catalogue with spectral indices and multi-wavelength classifications, and compares traditional and P(D) confusion count estimates.

Findings

Detected 558 sources above 5σ with 8 arcsec resolution.

Median spectral index of -0.76, flattening at lower flux densities.

Good agreement between traditional and P(D) source count estimates.

Abstract

This is the second of two papers describing the observations and source catalogues derived from sensitive 3-GHz images of the Lockman Hole North using the Karl G. Jansky Very Large Array. We describe the reduction and cataloguing process, which yielded an image with 8 arcsec resolution and instrumental noise of \sigma$_{\rm n}$=1.0 \mu Jy beam$^{-1}$ rms (before primary beam corrections) and a catalogue of 558 sources detected above 5\sigma$_{\rm n}$. We include details of how we estimate source spectral indices across the 2-GHz VLA bandwidth, finding a median index of -0.76$\pm$0.04. Stacking of source spectra reveals a flattening of spectral index with decreasing flux density. We present a source count derived from the catalogue. We show a traditional count estimate compared with a completely independent estimate made via a P(D) confusion analysis, and find very good agreement. Cross-matches of the catalogue with X-ray, optical, infrared, radio, and redshift catalogues are also presented. The X-ray, optical and infrared data, as well as AGN selection criteria allow us to classify 10 per cent as radio-loud AGN, 28 percent as radio-quiet AGN, and 58 per cent as star-forming galaxies, with only 4 per cent unclassified.