A Planck-selected dusty proto-cluster at z = 2.16 associated with a strong overdensity of massive Hα-emitting galaxies. Issue 1 (1st March 2021)

• Record Type: Journal Article
• Authors: Koyama, Yusei; Polletta, Maria del Carmen; Tanaka, Ichi; Kodama, Tadayuki; Dole, Hervé; Soucail, Geneviève; Frye, Brenda; Lehnert, Matthew; Scodeggio, Marco
• Is Part Of: Monthly notices of the Royal Astronomical Society. Volume 503:Issue 1(2021)
• Page Start: L1
• Page End: L5
• Publication Date: 2021-03-01
• Subjects: galaxies: clusters: general -- galaxies: evolution -- galaxies: star formation; Astronomy -- Research -- Periodicals; Periodicals; 520.5
• DOI: 10.1093/mnrasl/slab013
• Languages: English
• ISSNs: 1745-3933

Abstract

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 arcmin 2 field (corresponding to ∼2.0 × 3.5 Mpc 2 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.