Dependence of the build-up of the colour-magnitude relation on cluster richness at z ∼ 0.8

Yusei Koyama, Tadayuki Kodama, Masayuki Tanaka, Kazuhiro Shimasaku, Sadanori Okamura

Research output: Contribution to journalArticlepeer-review

25 Citations (Scopus)


We present environmental dependence of the build-up of the colour-magnitude relation (CMR) at z ∼ 0.8. It is well established that massive early-type galaxies exhibit a tight CMR in clusters up to at least z ∼ 1. The faint end of the relation, however, has been much less explored especially at high redshifts primarily due to limited depths of the data. Some recent papers have reported a deficit of the faint red galaxies on the CMR at 0.8 ≲ z ≲ 1, but this has not been well confirmed yet and is still controversial. Using a deep, multi-colour, panoramic imaging data set of the distant cluster RXJ1716.4+6708 at z = 0.81, newly taken with the Prime Focus Camera (Suprime-Cam) on the Subaru Telescope, we carry out an analysis of faint red galaxies, taking care not to underestimate the number of these galaxies. We find that there is a sharp decline in the number of red galaxies toward the faint end of the CMR below M* + 2. We compare our result with those for other clusters at z ∼ 0.8 taken from the literature, which show or do not show the deficit. We suggest that the 'deficit' of faint red galaxies is dependent on the richness or mass of the clusters, in the sense that poorer systems show stronger deficits. This indicates that the evolutionary stage of less massive galaxies depends critically on environment.

Original languageEnglish
Pages (from-to)1719-1728
Number of pages10
JournalMonthly Notices of the Royal Astronomical Society
Issue number4
Publication statusPublished - 2007 Dec
Externally publishedYes


  • Galaxies: clusters: individual: RXJ1716.4+6708
  • Galaxies: evolution
  • Galaxies: luminosity function, mass function

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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