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Clustering of galaxies at 3.6 μm in the Spitzer Wide-area Infrared Extragalactic legacy survey

Waddington, I. and Oliver, S. J. and Babbedge, T. S. R. and Fang, F. and Farrah, D. and Franceschini, A. and Gonzalez-Solares, E. A. and Lonsdale, C. J. and Rodighiero, G. and Rowan-Robinson, M. and Shupe, D. L. and Surace, J. A. and Vaccari, M. and Xu, C. K. (2007) Clustering of galaxies at 3.6 μm in the Spitzer Wide-area Infrared Extragalactic legacy survey. Monthly Notices of the Royal Astronomical Society, 381 (4). pp. 1437-1449. ISSN 0035-8711. doi:10.1111/j.1365-2966.2007.12367.x.

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We investigate the clustering of galaxies selected in the 3.6 μm band of the Spitzer Wide-area Infrared Extragalactic (SWIRE) legacy survey. The angular two-point correlation function is calculated for 11 samples with flux limits of S_(3.6)≥ 4–400 μJy, over an 8 deg^2 field. The angular clustering strength is measured at >5σ significance at all flux limits, with amplitudes of A = (0.49–29) × 10^(−3) at 1°, for a power-law model, Aθ^(−0.8). We estimate the redshift distributions of the samples using phenomological models, simulations and photometric redshifts, and so derive the spatial correlation lengths. We compare our results with the Galaxies In Cosmological Simulations (GalICS) models of galaxy evolution and with parametrized models of clustering evolution. The GalICS simulations are consistent with our angular correlation functions, but fail to match the spatial clustering inferred from the phenomological models or the photometric redshifts. We find that the uncertainties in the redshift distributions of our samples dominate the statistical errors in our estimates of the spatial clustering. At low redshifts (median z ≤ 0.5), the comoving correlation length is approximately constant, r_0= 6.1 ± 0.5 h^(−1) Mpc, and then decreases with increasing redshift to a value of 2.9 ± 0.3 h^(−1) Mpc for the faintest sample, for which the median redshift is z ~ 1. We suggest that this trend can be attributed to a decrease in the average galaxy and halo mass in the fainter flux-limited samples, corresponding to changes in the relative numbers of early- and late-type galaxies. However, we cannot rule out strong evolution of the correlation length over 0.5 < z < 1 .

Item Type:Article
Related URLs:
URLURL TypeDescription
Oliver, S. J.0000-0001-7862-1032
Farrah, D.0000-0003-1748-2010
Lonsdale, C. J.0000-0003-0898-406X
Rodighiero, G.0000-0002-9415-2296
Shupe, D. L.0000-0003-4401-0430
Surace, J. A.0000-0001-7291-0087
Vaccari, M.0000-0002-6748-0577
Xu, C. K.0000-0002-1588-6700
Additional Information:© 2007 The Authors. Journal compilation © 2007 RAS. Accepted 2007 August 15. Received 2007 July 26; in original form 2006 October 4. Published Online: 26 Oct 2007. The pair-counting code NPT was provided by The Auton Lab at Carnegie Mellon University’s School of Computer Science ( and we thank Andrew Moore et al. for making this software public. This work was funded by PPARC research grants to Seb Oliver. Support for this work, part of the Spitzer Space Telescope Legacy Science Programme, was provided by NASA through a contract issued by the Jet Propulsion Laboratory, California Institute of Technology under a contract with NASA.
Group:Infrared Processing and Analysis Center (IPAC)
Funding AgencyGrant Number
Particle Physics and Astronomy Research Council (PPARC)UNSPECIFIED
Subject Keywords:galaxies: evolution; galaxies: statistics; large-scale structure of Universe; infrared: galaxies
Issue or Number:4
Record Number:CaltechAUTHORS:20091130-115833206
Persistent URL:
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:16835
Deposited By: Jason Perez
Deposited On:30 Nov 2009 23:18
Last Modified:08 Nov 2021 23:30

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