The environmental impacts on the star formation main sequence: An Hα study of the newly discovered rich cluster at z = 1.52

Yusei Koyama, Tadayuki Kodama, Ken Ichi Tadaki, Masao Hayashi, Ichi Tanaka, Rhythm Shimakawa

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36 Citations (Scopus)

Abstract

We report the discovery of a strong over-density of galaxies in the field of a radio galaxy at z = 1.52 (4C 65.22) based on our broadband and narrow-band (Hα) photometry with the Subaru Telescope. We find that Hα emitters are located in the outskirts of the density peak (cluster core) dominated by passive red-sequence galaxies. This resembles the situation in lower-redshift clusters, suggesting that the newly discovered structure is a well-evolved rich galaxy cluster at z = 1.5. Our data suggest that the color-density and stellar mass-density relations are already in place at z ∼ 1.5, mostly driven by the passive red massive galaxies residing within rc ≲ 200 kpc from the cluster core. These environmental trends almost disappear when we consider only star-forming (SF) galaxies. We do not find SFR-density or SSFR-density relations amongst SF galaxies, and the location of the SF main sequence does not significantly change with environment. Nevertheless, we find a tentative hint that star-bursting galaxies (up-scattered objects from the main sequence) are preferentially located in a small group at ∼1 Mpc away from the main body of the cluster. We also argue that the scatter of the SF main sequence could be dependent on the distance to the nearest neighboring galaxy.

Original languageEnglish
Article number18
JournalAstrophysical Journal
Volume789
Issue number1
DOIs
Publication statusPublished - 2014 Jul 1

Keywords

  • galaxies: active
  • galaxies: clusters: general
  • galaxies: evolution

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