Luminosity functions for galaxies and quasars in the Spitzer Wide-area Infrared Extragalactic Legacy Survey

Babbedge, T.S.R.; Rowan-Robinson, M.; Vaccari, M.; Surace, J.A.; Lonsdale, C.J.; Clements, D.L.; Fang, F.; Farrah, D.; Franceschini, A.; Gonzalez-Solares, E.; Hatziminaoglou, E.; Lacey, C.G.; Oliver, S.; Onyett, N.; Pérez-Fournon, I.; Polletta, M.; Pozzi, F.; Rodighiero, G.; Shupe, D.L.; Siana, B.; Smith, H.E.

doi:10.1111/j.1365-2966.2006.10547.x

Luminosity functions for galaxies and quasars in the Spitzer Wide-area Infrared Extragalactic Legacy Survey

Babbedge, T.S.R.; Rowan-Robinson, M.; Vaccari, M.; Surace, J.A.; Lonsdale, C.J.; Clements, D.L.; Fang, F.; Farrah, D.; Franceschini, A.; Gonzalez-Solares, E.; Hatziminaoglou, E.; Lacey, C.G.; Oliver, S.; Onyett, N.; Pérez-Fournon, I.; Polletta, M.; Pozzi, F.; Rodighiero, G.; Shupe, D.L.; Siana, B.; Smith, H.E.

Authors

T.S.R. Babbedge

M. Rowan-Robinson

M. Vaccari

J.A. Surace

C.J. Lonsdale

D.L. Clements

F. Fang

D. Farrah

A. Franceschini

E. Gonzalez-Solares

E. Hatziminaoglou

Professor Cedric Lacey cedric.lacey@durham.ac.uk
Professor

S. Oliver

N. Onyett

I. Pérez-Fournon

M. Polletta

F. Pozzi

G. Rodighiero

D.L. Shupe

B. Siana

H.E. Smith

Abstract

We construct rest-frame luminosity functions (LFs) at 3.6, 4.5, 5.8, 8 and 24 μm over the redshift range 0 < z < 2 for galaxies and 0 < z < 4 for optical quasi-stellar objects (QSOs), using optical and infrared (IR) data from the Spitzer Wide-area Infrared Extragalactic (SWIRE) Survey. The 3.6- and 4.5-μm galaxy LFs show evidence for moderate positive luminosity evolution up to z∼ 1.5, consistent with the passive ageing of evolved stellar populations. Their comoving luminosity density was found to evolve passively, gradually increasing out to z∼ 0.5–1 but flattening, or even declining, at higher redshift. Conversely, the 24-μm galaxy LF, which is more sensitive to obscured star formation and/or active galactic nuclei (AGN) activity, undergoes strong positive evolution, with the derived IR energy density and star formation rate (SFR) density ∝ (1 +z)γ with γ= 4.5+0.7−0.6 and the majority of this evolution occurring since z∼ 1. Optical QSOs, however, show positive luminosity evolution in all bands, out to the highest redshifts (3 < z < 4). Modelling as L*∝ (1 +z)γ gave γ= 1.3+0.1−0.1 at 3.6 μm, γ= 1.0+0.1−0.1 at 4.5 μm and stronger evolution at the longer wavelengths (5.8, 8 and 24 μm), of γ∼ 3. Comparison of the galaxy LFs to predictions from a semi-analytic model based on cold dark matter (CDM) indicates that an initial mass function (IMF) skewed towards higher mass star formation in bursts compared to locally be preferred. As a result, the currently inferred massive SFRs in distant submm sources may require substantial downwards revision.

Citation

Babbedge, T., Rowan-Robinson, M., Vaccari, M., Surace, J., Lonsdale, C., Clements, D., …Smith, H. (2006). Luminosity functions for galaxies and quasars in the Spitzer Wide-area Infrared Extragalactic Legacy Survey. Monthly Notices of the Royal Astronomical Society, 370(3), 1159-1180. https://doi.org/10.1111/j.1365-2966.2006.10547.x

Journal Article Type	Article
Publication Date	Aug 11, 2006
Deposit Date	Jun 27, 2014
Publicly Available Date	Jan 29, 2015
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	370
Issue	3
Pages	1159-1180
DOI	https://doi.org/10.1111/j.1365-2966.2006.10547.x
Keywords	Galaxies: evolution, Galaxies: photometry, Quasars: general, Cosmology: observations.

Files

Published Journal Article (775 Kb)
PDF

Copyright Statement
This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society © 2006 The Authors. Published by Oxford University Press on behalf of The Royal Astronomical Society. All rights reserved.