Babbedge, T. S. R. and Rowan-Robinson, M. and Vaccari, M. and Surace, J. A. and Lonsdale, C. J. and Clements, D. L. and Fang, F. and Farrah, D. and Franceschini, A. and Gonzalez-Solares, E. and Hatziminaoglou, E. and Lacey, C. G. and Oliver, S. and Onyett, N. and Pérez-Fournon, I. and Polletta, M. and Pozzi, F. and Rodighiero, G. and Shupe, D. L. and Siana, B. and Smith, H. E. (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). pp. 1159-1180. ISSN 0035-8711 http://resolver.caltech.edu/CaltechAUTHORS:20110216-083108180
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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.
|Additional Information:||© 2006 The Authors. Journal compilation © 2006 RAS. Accepted 2006 May 11. Received 2006 May 8; in original form 2006 February 16. Article first published online: 21 Jun. 2006 This work makes use of observations made with the Spitzer Space Telescope, operated by the Jet Propulsion Laboratory, CALTECH, NASA contract 1407. The INT WFS data are publicly available through the Isaac Newton Groups’ Wide-Field Camera Survey Programme. SJO was supported by a Leverhulme Research Fellowship and PPARC grant PPA/G/S/2000/00508. TSRB and NO were supported by PPARC studentships. TSRB would like to thank Richard Savage for advice on expectation measures and Payam Davoodi for bimodality discussions. We extend our thanks to the referee.|
|Subject Keywords:||galaxies: evolution;galaxies: photometry;quasars: general;cosmology: observations|
|Official Citation:||Luminosity functions for galaxies and quasars in the Spitzer Wide-area Infrared Extragalactic Legacy Survey (pages 1159–1180) 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, C. G. Lacey, S. Oliver, N. Onyett, I. Pérez-Fournon, M. Polletta, F. Pozzi, G. Rodighiero, D. L. Shupe, B. Siana and H. E. Smith Article first published online: 21 JUN 2006 | DOI: 10.1111/j.1365-2966.2006.10547.|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Ruth Sustaita|
|Deposited On:||16 Feb 2011 17:12|
|Last Modified:||16 Feb 2011 17:12|
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