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

Ryan Quadri, Danilo Marchesini, Pieter Van Dokkum, Eric Gawiser, Marijn Franx, Paulina Lira, Gregory Rudnick, C. Megan Urry, José Maza, Mariska Kriek, L. Felipe Barrientos, Guillermo A. Blanc, Francisco J. Castander, Daniel Christlein, Paolo S. Coppi, Patrick B. Hall, David Herrera, Leopoldo Infante, Edward N. Taylor, Ezequiel TreisterJon P. Willis

Research output: Contribution to journalArticlepeer-review

81 Scopus citations


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.

Original languageEnglish (US)
Pages (from-to)1103-1117
Number of pages15
JournalAstronomical Journal
Issue number3
StatePublished - Sep 2007

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


  • Catalogs
  • Galaxies: distances and redshifts
  • Galaxies: high-redshift
  • Infrared: galaxies
  • Surveys


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