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Accepted manuscript

EMU/GAMA: A new approach to characterising radio luminosity functions

Published online by Cambridge University Press:  02 June 2025

J. Prathap Open the ORCID record for J. Prathap [Opens in a new window] ,
A. M. Hopkins Open the ORCID record for A. M. Hopkins [Opens in a new window] ,
J. Afonso ,
M. Bilicki ,
M. Cowley ,
S. M. Croom ,
Y. Gordon ,
S. Phillipps ,
E. M. Sadler  and
S. S. Shabala Open the ORCID record for S. S. Shabala [Opens in a new window]
...Show all authors
J. Prathap*
Affiliation:
School of Mathematical and Physical Sciences, Macquarie University, Sydney, NSW 2109, Australia Macquarie University Astrophysics and Space Technologies Research Centre, Sydney, NSW 2109, Australia
A. M. Hopkins
Affiliation:
School of Mathematical and Physical Sciences, Macquarie University, Sydney, NSW 2109, Australia Macquarie University Astrophysics and Space Technologies Research Centre, Sydney, NSW 2109, Australia
J. Afonso
Affiliation:
Instituto de Astrofísica e Ciências do Espaço, Universidade de Lisboa, OAL, Tapada da Ajuda, PT1349-018 Lisbon, Portugal Departamento de Física, Faculdade de Ciências, Universidade de Lisboa, Edifécio C8, Campo Grande, PT1749-016 Lisbon
M. Bilicki
Affiliation:
Centre for Theoretical Physics, Polish Academy of Sciences, Al. Lotników 32/46, 02-668 Warsaw, Poland
M. Cowley
Affiliation:
School of Chemistry and Physics, Queensland University of Technology, Brisbane, QLD, Australia Centre for Astrophysics, University of Southern Queensland, West Street, Toowoomba, QLD 4350, Australia
S. M. Croom
Affiliation:
Sydney Institute for Astronomy (SIfA), School of Physics, A28, The University of Sydney, NSW 2006, Australia
Y. Gordon
Affiliation:
Physics Department, 2320 Chamberlin Hall, University of Wisconsin-Madison, 1150 University Avenue Madison, WI 53706-1390, USA
S. Phillipps
Affiliation:
Astrophysics Group, School of Physics, University of Bristol, Tyndall Avenue, Bristol BS8 1TL, UK
E. M. Sadler
Affiliation:
Sydney Institute for Astronomy (SIfA), School of Physics, A28, The University of Sydney, NSW 2006, Australia CSIRO Space and Astronomy, PO Box 76, Epping NSW 1710, Australia
S. S. Shabala
Affiliation:
School of Natural Sciences, University of Tasmania, Private Bag 37, Hobart, Tasmania 7001, Australia
U. T. Ahmed
Affiliation:
Macquarie University Astrophysics and Space Technologies Research Centre, Sydney, NSW 2109, Australia Australian Astronomical Optics, Macquarie University, 105 Delhi Rd, North Ryde, NSW 2113, Australia Centre for Astrophysics, University of Southern Queensland, 37 Sinnathamby Boulevard, Springfield Central, QLD 4300, Australia
S. Amarantidis
Affiliation:
Institut de Radioastronomie Millimétrique (IRAM), Avenida Divina Pastora 7, Local 20, E-18012, Granada, Spain
M. J. I. Brown
Affiliation:
School of Physics, Monash University, Clayton, VIC 3800, Australia
R. Carvajal
Affiliation:
Instituto de Astrofísica e Ciências do Espaço, Universidade de Lisboa, OAL, Tapada da Ajuda, PT1349-018 Lisbon, Portugal Departamento de Física, Faculdade de Ciências, Universidade de Lisboa, Edifécio C8, Campo Grande, PT1749-016 Lisbon
D. Leahy
Affiliation:
Department of Physics and Astronomy, University of Calgary, Calgary, AB T2N 1N4, Canada
J. R. Marvil
Affiliation:
National Radio Astronomy Observatory, P.O. Box O, Socorro, NM 87801, USA
T. Mukherjee
Affiliation:
School of Mathematical and Physical Sciences, Macquarie University, Sydney, NSW 2109, Australia Macquarie University Astrophysics and Space Technologies Research Centre, Sydney, NSW 2109, Australia
J. Willingham
Affiliation:
School of Mathematical and Physical Sciences, Macquarie University, Sydney, NSW 2109, Australia Macquarie University Astrophysics and Space Technologies Research Centre, Sydney, NSW 2109, Australia
T. Zafar
Affiliation:
School of Mathematical and Physical Sciences, Macquarie University, Sydney, NSW 2109, Australia Macquarie University Astrophysics and Space Technologies Research Centre, Sydney, NSW 2109, Australia
*
Author for correspondence: J. Prathap, Email: jahangprathap12@gmail.com.
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Abstract

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This study characterises the radio luminosity functions (RLFs) for SFGs and AGN using statistical redshift estimation in the absence of comprehensive spectroscopic data. Sensitive radio surveys over large areas detect many sources with faint optical and infrared counterparts, for which redshifts and spectra are unavailable. This challenges our attempt to understand the population of radio sources. Statistical tools are often used to model parameters (such as redshift) as an alternative to observational data. Using the data from GAMA G23 and EMU early science observations, we explore simple statistical techniques to estimate the redshifts in order to measure the RLFs of the G23 radio sources as a whole and for SFGs and AGN separately. Redshifts and AGN/SFG classifications are assigned statistically for those radio sources without spectroscopic data. The calculated RLFs are compared with existing studies, and the results suggest that the RLFs match remarkably well for low redshift galaxies with an optical counterpart. We use a more realistic high redshift distribution to model the redshifts of (most likely) high redshift radio sources and find that the LFs from our approach match well with measured LFs. We also look at strategies to compare the RLFs of radio sources without an optical counterpart to existing studies.

Keywords

radio luminosity functionsradio AGNradio surveysstatistical techniques
Type
Research Article
Information
Publications of the Astronomical Society of Australia , Accepted manuscript , pp. 1 - 17
Creative Commons
Creative Common License - CCCreative Common License - BY
This is an Open Access article, distributed under the terms of the Creative Commons Attribution licence (https://creativecommons.org/licenses/by/4.0/), which permits unrestricted re-use, distribution and reproduction, provided the original article is properly cited.
Copyright
© The Author(s), 2025. Published by Cambridge University Press on behalf of Astronomical Society of Australia