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Published January 1, 2010 | Published
Journal Article Open

The COSMOS-WIRCam Near-Infrared Imaging Survey. I. BzK-Selected Passive and Star-Forming Galaxy Candidates at z ≳ 1.4


We present a new near-infrared survey covering the 2 deg^2 COSMOS field conducted using WIRCam at the Canada-France-Hawaii Telescope. By combining our near-infrared data with Subaru B and z images, we construct a deep, wide-field optical-infrared catalog. At K_s < 23 (AB magnitudes), our survey completeness is greater than 90% and 70% for stars and galaxies, respectively, and contains 143,466 galaxies and 13,254 stars. Using the BzK diagram, we divide our galaxy catalog into quiescent and star-forming galaxy candidates. At z ~ 2, our catalogs contain 3931 quiescent and 25,757 star-forming galaxies representing the largest and most secure sample at these depths and redshifts to date. Our counts of quiescent galaxies turns over at K_s ~ 22, an effect that we demonstrate cannot be due to sample incompleteness. Both the number of faint and bright quiescent objects in our catalogs exceed the predictions of a recent semi-analytic model of galaxy formation, indicating potentially the need for further refinements in the amount of merging and active galactic nucleus feedback at z ~ 2 in these models. We measure the angular correlation function for each sample and find that the slope of the field galaxy correlation function flattens to 1.5 by K_s ~ 23. At small angular scales, the angular correlation function for passive BzK galaxies is considerably in excess of the clustering of dark matter. We use precise 30-band photometric redshifts to derive the spatial correlation length and the redshift distributions for each object class. At K_s < 22, we find r^(γ/1.8)_0 = 7.0 ± 0.5 h^(–1) Mpc for the passive BzK candidates and 4.7 ± 0.8 h^(–1) Mpc for the star-forming BzK galaxies. Our pBzK galaxies have an average photometric redshift of z_p ~ 1.4, in approximate agreement with the limited spectroscopic information currently available. The stacked K_s image will be made publicly available from IRSA.

Additional Information

© 2010 American Astronomical Society. Print publication: Issue 1 (2010 January 1); received 2009 March 6; accepted for publication 2009 November 9; published 2009 December 9. This work is based in part on data products produced at TERAPIX at the Institut d'Astrophysique de Paris. H.J.McC. acknowledges the use of TERAPIX computing facilities and the hospitality of the IfA, Honolulu, where this paper was finished. M. Kilbinger is acknowledged for help with dark matter models in Section 6 and N.V. Asari for the stacking analysis in Section 4. This research has made use of the VizieR catalog access tool provided by the CDS, Strasbourg, France. This research was supported by ANR grant "ANR-07-BLAN-0228." E.D. and C.M. also acknowledge support from "ANR-08-JCJC-0008." J.P.K. acknowledges support from the CNRS. We thank the referee for an extensive commentary on a earlier version of this paper.

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Published - McCracken2010p6752Astrophys_J.pdf


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