Galaxy And Mass Assembly (GAMA): the 325 MHz radio luminosity function of AGN and star-forming galaxies

Prescott, M.; Mauch, T.; Jarvis, M.J.; McAlpine, K.; Smith, D.J.B.; Fine, S.; Johnston, R.; Hardcastle, M.J.; Baldry, I.K.; Brough, S.; Brown, M.J.I.; Bremer, M.N.; Driver, S.P.; Hopkins, A.M.; Kelvin, L.S.; Loveday, J.; Norberg, P.; Obreschkow, D.; Sadler, E.M.

doi:10.1093/mnras/stv3020

Galaxy And Mass Assembly (GAMA): the 325 MHz radio luminosity function of AGN and star-forming galaxies

Prescott, M.; Mauch, T.; Jarvis, M.J.; McAlpine, K.; Smith, D.J.B.; Fine, S.; Johnston, R.; Hardcastle, M.J.; Baldry, I.K.; Brough, S.; Brown, M.J.I.; Bremer, M.N.; Driver, S.P.; Hopkins, A.M.; Kelvin, L.S.; Loveday, J.; Norberg, P.; Obreschkow, D.; Sadler, E.M.

Authors

M. Prescott

T. Mauch

M.J. Jarvis

K. McAlpine

D.J.B. Smith

S. Fine

R. Johnston

M.J. Hardcastle

I.K. Baldry

S. Brough

M.J.I. Brown

M.N. Bremer

S.P. Driver

A.M. Hopkins

L.S. Kelvin

J. Loveday

Professor Peder Norberg peder.norberg@durham.ac.uk
Professor

D. Obreschkow

E.M. Sadler

Abstract

Measurement of the evolution of both active galactic nuclei (AGN) and star-formation in galaxies underpins our understanding of galaxy evolution over cosmic time. Radio continuum observations can provide key information on these two processes, in particular via the mechanical feedback produced by radio jets in AGN, and via an unbiased dust-independent measurement of star formation rates. In this paper, we determine radio luminosity functions at 325 MHz for a sample of AGN and star-forming galaxies by matching a 138 deg2 radio survey conducted with the Giant Metrewave Radio Telescope, with optical imaging and redshifts from the Galaxy And Mass Assembly survey. We find that the radio luminosity function at 325 MHz for star-forming galaxies closely follows that measured at 1.4 GHz. By fitting the AGN radio luminosity function out to z = 0.5 as a double power law, and parametrizing the evolution as Φ ∝ (1 + z)k, we find evolution parameters of k = 0.92 ± 0.95 assuming pure density evolution and k = 2.13 ± 1.96 assuming pure luminosity evolution. We find that the Low Excitation Radio Galaxies are the dominant population in space density at lower luminosities. Comparing our 325 MHz observations with radio continuum imaging at 1.4 GHz, we determine separate radio luminosity functions for steep- and flat-spectrum AGN, and show that the beamed population of flat-spectrum sources in our sample can be shifted in number density and luminosity to coincide with the unbeamed population of steep-spectrum sources, as is expected in the orientation-based unification of AGN

Citation

Prescott, M., Mauch, T., Jarvis, M., McAlpine, K., Smith, D., Fine, S., …Sadler, E. (2016). Galaxy And Mass Assembly (GAMA): the 325 MHz radio luminosity function of AGN and star-forming galaxies. Monthly Notices of the Royal Astronomical Society, 457(1), 730-744. https://doi.org/10.1093/mnras/stv3020

Journal Article Type	Article
Acceptance Date	Dec 30, 2015
Online Publication Date	Jan 25, 2016
Publication Date	Mar 21, 2016
Deposit Date	Apr 5, 2016
Publicly Available Date	Apr 7, 2016
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	457
Issue	1
Pages	730-744
DOI	https://doi.org/10.1093/mnras/stv3020
Related Public URLs	http://arxiv.org/abs/1601.00003

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This article has been published in Monthly Notices of the Royal Astronomical Society ©: 2016 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.