The multiwavelength survey by Yale-Chile (MUSYC): Deep near-infrared imaging and the selection of distant galaxies

We present deep near-infrared JHK imaging of four 10′ × 10′ fields. The observations were carried out as part of the Multiwavelength Survey by Yale-Chile (MUSYC) with ISPI on the CTIO 4 m telescope. The typical pointsource limiting depths are J ∼ 22.5, H ∼ 21.5, and K ∼ 21 (5 σ; Vega). The effective seeing in the final images is ∼ 1.0″. We combine these data with MUSYC UBVRIz imaging to create K-selected catalogs that are unique for their uniform size, depth, filter coverage, and image quality. We investigate the rest-frame optical colors and photometric redshifts of galaxies that are selected using common color selection techniques, including distant red galaxies (DRGs), star-forming and passive BzKs, and the rest-frame UV-selected BM, BX, and Lyman break galaxies (LBGs). These techniques are effective at isolating large samples of high-redshift galaxies, but none provide complete or uniform samples across the targeted redshift ranges. The DRG and BM/BX/LBG criteria identify populations of red and blue galaxies, respectively, as they were designed to do. The star-forming BzKs have a very wide redshift distribution, extending down to z ∼ 1, a wide range of colors, and may include galaxies with very low specific star formation rates. In comparison, the passive BzKs are fewer in number, have a different distribution of K magnitudes, and have a some-what different redshift distribution. By combining either the DRG and BM/BX/LBG criteria, or the star-forming and passive BzK criteria, it appears possible to define a reasonably complete sample of galaxies to our flux limit over specific redshift ranges. However, the redshift dependence of both the completeness and sampled range of rest-frame colors poses an ultimate limit to the usefulness of these techniques.