The first appearance of the red sequence of galaxies in proto-clusters at 2 ≲ z ≲ 3

Tadayuki Kodama, Ichi Tanaka, Masaru Kajisawa, Jaron Kurk, Bram Venemans, Carlos De Breuck, Joël Vernet, Chris Lidman

Research output: Contribution to journalArticlepeer-review

142 Citations (Scopus)


We explore the evolved galaxy population in the proto-clusters around four high-z radio galaxies at based on wide-field near-infrared (NIR) imaging. Three of the four fields are known proto-clusters as demonstrated by overdensities of line-emitting galaxies at the same redshifts as the radio galaxies found by narrow-band surveys and spectroscopic follow-up observations. We imaged the fields of three targets (PKS 1138-262, USS 0943-242 and MRC 0316-257) to a depth of (Vega magnitude, 5σ) over a area centred on the radio galaxies with a new wide-field NIR camera, Multi-Object Infra-Red Camera and Spectrograph (MOIRCS), on the Subaru Telescope. Another target (USS 1558-003) was observed with Son of ISAAC on the New technology Telescope (NTT) to a depth of over a area. We apply colour cuts in and/or in order to exclusively search for galaxies located at high redshifts:. To the 5σ limiting magnitudes, we see a significant excess of NIR-selected galaxies by a factor of 2 to 3 compared to those found in the field of GOODS-South. The spatial distribution of these NIR-selected galaxies is not uniform and traces structures similar to those of emission-line galaxies, although the samples of NIR-selected galaxies and emitters show little overlap, from which we conclude that the former tend to be an evolved population with much higher stellar mass than the latter, young and active emitters. We focus on the NIR colour-magnitude sequence of the evolved population and find that the bright-end of the red sequence is well populated by but much less so in the proto-clusters. This may imply that the bright-end of the colour-magnitude sequence first appeared between and 2, an era coinciding with the appearance of sub-mm galaxies and the peak of the cosmic star formation rate. Our observations show that during the same epoch, massive galaxies are forming in high-density environments by vigorous star formation and assembly.

Original languageEnglish
Pages (from-to)1717-1725
Number of pages9
JournalMonthly Notices of the Royal Astronomical Society
Issue number4
Publication statusPublished - 2007 Jun
Externally publishedYes


  • Galaxies: clusters: general
  • Galaxies: evolution
  • Galaxies: formation
  • Galaxies: high-redshift

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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