A Planck-selected dusty proto-cluster at z = 2.16 associated with a strong overdensity of massive Hα-emitting galaxies

Yusei Koyama, Maria Del Carmen Polletta, Ichi Tanaka, Tadayuki Kodama, Hervé Dole, Geneviève Soucail, Brenda Frye, Matthew Lehnert, Marco Scodeggio

Research output: Contribution to journalArticlepeer-review

Abstract

We have discovered an overdensity of Hα-emitting galaxies associated with a Planck compact source in the COSMOS field (PHz G237.0+42.5) through narrow-band imaging observations with the Subaru Multi-Object InfraRed Camera and Spectrograph (MOIRCS). This Planck-selected dusty proto-cluster at z = 2.16 has 38 Hα emitters including six spectroscopically confirmed galaxies in the observed MOIRCS 4 × 7 arcmin2 field (corresponding to ∼2.0 × 3.5 Mpc2 in the physical scale). We find that massive Hα emitters with log (M/M) >10.5 are strongly clustered in the core of the proto-cluster (within ∼300 kpc from the density peak of the Hα emitters). Most of the Hα emitters in this proto-cluster lie along the star-forming main sequence using Hα-based estimates of the star formation rate (SFR). Meanwhile, the cluster total SFRs derived by integrating the Hα-based SFRs is an order of magnitude smaller than those estimated from Planck/Herschel far-infrared photometry. Our results suggest that Hα is a good observable for detecting moderately star-forming galaxies and for tracing the large-scale environment in and around high-redshift dusty proto-clusters. However, there is a possibility that a large fraction of star formation could be obscured by dust and undetected in Hα observations.

Original languageEnglish (US)
Pages (from-to)L1-L5
JournalMonthly Notices of the Royal Astronomical Society: Letters
Volume503
Issue number1
DOIs
StatePublished - May 1 2021

Keywords

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

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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