Chen, Hsiao-Wen et al. (19 authors including P. Martini) 2002, ApJ, 570, 54
The Las Campanas Infrared Survey, based on broad-band optical and near-infrared photometry, is designed to robustly identify a statistically significant and representative sample of evolved galaxies at redshifts z>1. We have completed an H-band imaging survey over 1.1 square degrees of sky in six separate fields. The average 5-sigma detection limit in a four arcsecond diameter aperture is H~20.8. Here we describe the design of the survey, the observation strategies, data reduction techniques, and object identification procedures. We present sample near-infrared and optical photometric catalogs for objects identified in two survey fields. The optical images of the Hubble Deep Field South region obtained from the literature reach 5-sigma detection thresholds in a four arcsecond diameter aperture of U~24.6, B~26.1, V~25.6, R~25.1, and I~24.2 magnitude. The optical images of the Chandra Deep Field South region obtained from our own observations reach 5-sigma detection thresholds in a four arcsecond diameter aperture of V~26.8, R~26.2, I~25.3, and z'~23.7 mag. We perform object detection in all bandpasses and identify ~54,000 galaxies over 1,408 arcmin2 of sky in the two fields. Of these galaxies, ~14,000 are detected in the H-band and ~2,000 have the colors of evolved galaxies, I-H>3, at z~1. We find that (1) the differential number counts N(m) for the H-band detected objects has a slope of dlog N(m)/dm = 0.44 mag-2 at H~19 and 0.27 mag-2 at H~19 with a mean surface density ~7,200 degree-2 mag-1 at H = 19. In addition, we find that (2) the differential number counts for the H-band detected red objects has a very steep slope, dlog N(m I-H > 3)/dm = 0.83 mag-2 at H<20 and 0.32 mag-2 at H>20, with a mean surface density ~3,000 degree-2 mag^-1 at H=20. Finally, we find that (3) galaxies with red optical to near-IR colors (I-H > 3) constitute ~20% of the H-band detected galaxies at H<21, but only ~2% at H<19. We show that red galaxies are strongly clustered, which results in a strong field to field variation in their surface density. Comparisons of observations and predictions based on various formation scenarios indicate that these red galaxies are consistent with mildly evolving early-type galaxies at z~1, although with a significant amount of on-going star formation as indicated by the large scatter in their V-I colors.
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