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MIGHTEE: deep 1.4 GHz source counts and the sky temperature contribution of star-forming galaxies and active galactic nuclei

Hale, CL; Whittam, IH; Jarvis, MJ; Best, PN; Thomas, NL; Heywood, I; Prescott, M; Adams, N; Afonso, J; An, Fangxia; Bowler, RAA; Collier, JD; Cook, RHW; Davé, R; Frank, BS; Glowacki, M; Hatfield, PW; Kolwa, S; Lovell, CC; Maddox, N; Marchetti, L; Morabito, LK; Murphy, E; Prandoni, I; Randriamanakoto, Z; Taylor, AR

MIGHTEE: deep 1.4 GHz source counts and the sky temperature contribution of star-forming galaxies and active galactic nuclei Thumbnail


Authors

CL Hale

IH Whittam

MJ Jarvis

PN Best

I Heywood

M Prescott

N Adams

J Afonso

Fangxia An

RAA Bowler

JD Collier

RHW Cook

R Davé

BS Frank

M Glowacki

PW Hatfield

S Kolwa

CC Lovell

N Maddox

L Marchetti

E Murphy

I Prandoni

Z Randriamanakoto

AR Taylor



Abstract

We present deep 1.4 GHz source counts from ∼5 deg2 of the continuum Early Science data release of the MeerKAT International Gigahertz Tiered Extragalactic Exploration survey down to S1.4GHz ∼15 μ Jy. Using observations over two extragalactic fields (COSMOS and XMM-LSS), we provide a comprehensive investigation into correcting the incompleteness of the raw source counts within the survey to understand the true underlying source count population. We use a variety of simulations that account for: errors in source detection and characterization, clustering, and variations in the assumed source model used to simulate sources within the field and characterize source count incompleteness. We present these deep source count distributions and use them to investigate the contribution of extragalactic sources to the sky background temperature at 1.4 GHz using a relatively large sky area. We then use the wealth of ancillary data covering a subset of the COSMOS field to investigate the specific contributions from both active galactic nuclei (AGN) and star-forming galaxies (SFGs) to the source counts and sky background temperature. We find, similar to previous deep studies, that we are unable to reconcile the sky temperature observed by the ARCADE 2 experiment. We show that AGN provide the majority contribution to the sky temperature contribution from radio sources, but the relative contribution of SFGs rises sharply below 1 mJy, reaching an approximate 15–25 per cent contribution to the total sky background temperature (Tb ∼100 mK) at ∼15 μ Jy.

Citation

Hale, C., Whittam, I., Jarvis, M., Best, P., Thomas, N., Heywood, I., …Taylor, A. (2023). MIGHTEE: deep 1.4 GHz source counts and the sky temperature contribution of star-forming galaxies and active galactic nuclei. Monthly Notices of the Royal Astronomical Society, 520(2), 2668 - 2691. https://doi.org/10.1093/mnras/stac3320

Journal Article Type Article
Acceptance Date Nov 8, 2022
Online Publication Date Nov 18, 2022
Publication Date 2023-04
Deposit Date May 11, 2023
Publicly Available Date Mar 29, 2024
Journal Monthly Notices of the Royal Astronomical Society
Print ISSN 0035-8711
Electronic ISSN 1365-2966
Publisher Royal Astronomical Society
Peer Reviewed Peer Reviewed
Volume 520
Issue 2
Pages 2668 - 2691
DOI https://doi.org/10.1093/mnras/stac3320

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