LoCuSS: pre-processing in galaxy groups falling into massive galaxy clusters at z = 0.2

Matteo Bianconi, Graham P. Smith, C. P. Haines, Sean McGee, A Finoguenov, E Egami

Research output: Contribution to journalLetterpeer-review

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Abstract

We report direct evidence of pre-processing of the galaxies residing in galaxy groups falling into galaxy clusters drawn from the Local Cluster Substructure Survey (LoCuSS). 34 groups have been identified via their X-ray emission in the infall regions of 23 massive (〈M200〉 = 1015 M) clusters at 0.15 < z < 0.3. Highly complete spectroscopic coverage combined with 24 μm imaging from Spitzer allows us to make a consistent and robust selection of cluster and group members including star-forming galaxies down to a stellar mass limit of M = 2 × 1010 M. The fraction fSF of star-forming galaxies in infalling groups is lower and with a flatter trend with respect to clustercentric radius when compared to the rest of the cluster galaxy population. At R ≈ 1.3 r200, the fraction of star-forming galaxies in infalling groups is half that in the cluster galaxy population. This is direct evidence that star-formation quenching is effective in galaxies already prior to them settling in the cluster potential, and that groups are favourable locations for this process.
Original languageEnglish
Pages (from-to)L79–L83
Number of pages5
JournalMonthly Notices of the Royal Astronomical Society
Volume473
Issue number1
Early online date12 Oct 2017
DOIs
Publication statusPublished - 1 Jan 2018

Keywords

  • galaxies: clusters: general
  • galaxies: evolution
  • galaxies: groups: general
  • galaxies: star formation

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