The space density and colors of massive galaxies at 2 < z < 3: The predominance of distant red galaxies

P. G. Van Dokkum, R. Quadri, D. Marchesini, G. Rudnick, M. Franx, E. Gawiser, D. Herrera, S. Wuyts, P. Lira, I. Labbé, J. Maza, G. D. Illingworth, N. M. Förster Schreiber, M. Kriek, H. W. Rix, E. N. Taylor, S. Toft, T. Webb, S. K. Yi

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144 Citations (Scopus)


Using the deep multiwavelength MUSYC, GOODS, and FIRES surveys we construct a stellar mass-limited sample of galaxies at 2<z<3. The sample comprises 294 galaxies with M>1011 M distributed over four independent fields with a total area of almost 400 arcmin2. The mean number density of massive galaxies in this redshift range p(M > 10 11 M) = (2.2 ± 0.6) × 10-4 h703 Mpc-3. We present median values and 25th and 75th percentiles for the distributions of observed RAB magnitudes, observed J - Ks colors, and rest-frame ultraviolet continuum slopes, M/LV ratios, and U - V colors. The galaxies show a large range in all these properties. The "median galaxy" is faint in the observer's optical (RAB = 25.9), red in the observed near-IR (J - Ks = 2.48), has a rest-frame UV spectrum that is relatively flat in Fλ (β = -0.4), and rest-frame optical colors resembling those of nearby spiral galaxies (U - V = 0.62). We determine which galaxies would be selected as Lyman break galaxies (LBGs) or distant red galaxies (DRGs, having J - Ks > 2.3) in this mass-limited sample. By number DRGs make up 69% of the sample, and LBGs 20%, with a small amount of overlap. By mass DRGs make up 77%, and LBGs 17%. Neither technique provides a representative sample of massive galaxies at 2 < z < 3 as they only sample the extremes of the population. As we show here, multiwavelength surveys with high-quality photometry are essential for an unbiased census of massive galaxies in the early universe. The main uncertainty in this analysis is our reliance on photometric redshifts; confirmation of the results presented here requires extensive near-infrared spectroscopy of optically faint samples.

Original languageEnglish
Pages (from-to)L59-L62
JournalAstrophysical Journal
Issue number2 II
Publication statusPublished - 2006 Feb 20

Bibliographical note

Funding Information:
We thank the anonymous referee for insightful comments that improved the manuscript significantly. P. G. v. D. acknowledges support from NSF CAREER AST-0449678. D. M. is supported by NASA LTSA NNG04GE12G. E. G. is supported by NSF Fellowship AST-0201667. S. T. is partly supported by the Danish Natural Research Council.

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


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