New constraints on the 1.4 GHz source number counts and luminosity functions in the Lockman Hole field. Issue 1 (17th October 2020)

• Record Type: Journal Article
• Authors: Bonato, Matteo; Prandoni, Isabella; De Zotti, Gianfranco; Brienza, Marisa; Morganti, Raffaella; Vaccari, Mattia
• Is Part Of: Monthly notices of the Royal Astronomical Society. Volume 500:Issue 1(2021)
• Page Start: 22
• Page End: 33
• Publication Date: 2020-10-17
• Subjects: galaxies: abundances -- galaxies: active -- galaxies: photometry -- submillimetre: galaxies; Astronomy -- Periodicals; Periodicals; 520.5
• DOI: 10.1093/mnras/staa3218
• Languages: English
• ISSNs: 0035-8711

Abstract

ABSTRACT: We present a study of the 1173 sources brighter than $S_{1.4\, \rm GHz}= 120\, \mu$ Jy detected over an area of $\simeq 1.4\, \hbox{deg}^{2}$ in the Lockman Hole field. Exploiting the multiband information available in this field for ∼79 per cent of the sample, sources have been classified into radio loud (RL) active galactic nuclei (AGNs), star-forming galaxies (SFGs), and radio quiet (RQ) AGNs, using a variety of diagnostics available in the literature. Exploiting the observed tight anticorrelations between IRAC band 1 or band 2 and the source redshift we could assign a redshift to 177 sources missing a spectroscopic measurement or a reliable photometric estimate. A Monte Carlo approach was used to take into account the spread around the mean relation. The derived differential number counts and luminosity functions at several redshifts of each population show a good consistency with models and with earlier estimates made using data from different surveys and applying different approaches. Our results confirm that below $\sim 300\, \mu$ Jy SFGs+RQ AGNs overtake RL AGNs that dominate at brighter flux densities. We also confirm earlier indications of a similar evolution of RQ AGNs and SFGs. Finally, we discuss the angular correlation function of our sources and highlight its sensitivity to the criteria used for the classification.