| Title | The Las Campanas Infrared Survey. III. The H-Band Imaging Survey and the Near-Infrared and Optical Photometric Catalogs |
| Authors | Chen, Hsiao-Wen; McCarthy, P. J.; Marzke, R. O.; Wilson, J.; Carlberg, R. G.; Firth, A. E.; Persson, S. E.; Sabbey, C. N.; Lewis, J. R.; McMahon, R. G.; Lahav, O.; Ellis, R. S.; Martini, P.; Abraham, R. G.; Oemler, A.; Murphy, D. C.; Somerville, R. S.; Beckett, M. G.; Mackay, C. D. |
| Bibcode | 2002ApJ...570...54C Search ADS ↗ |
| Abstract | The Las Campanas Infrared Survey, based on broadband 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 deg2 of sky in six separate fields. The average 5 σ detection limit in a 4" 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 σ detection thresholds in a 4" diameter aperture of U~24.6, B~26.1, V~25.6, R~25.1, and I~24.2 mag. The optical images of the Chandra Deep Field-South region obtained from our own observations reach 5 σ detection thresholds in a 4" 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 1408 arcmin2 of sky in the two fields. Of these galaxies, ~14,000 are detected in the H band and ~2000 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 dlogN(m)/dm=0.45+/-0.01 mag-2 at H<~19 and 0.27+/-0.01 mag-2 at H>~19, with a mean surface density ~7200 deg-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, dlogN(mI-H>~3)/dm=0.84+/-0.06 mag-2 at H<~20 and 0.32+/-0.07 mag-2 at H>~20, with a mean surface density ~3000 deg-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 ongoing star formation, as indicated by the large scatter in their V-I colors. |
| Objects | 27246 Objects Search NED ↙ |
