Evolutionary Phases of Gas-rich Galaxies in a Galaxy Cluster at z = 1.46

Masao Hayashi, Tadayuki Kodama, Kotaro Kohno, Yuki Yamaguchi, Ken Ichi Tadaki, Bunyo Hatsukade, Yusei Koyama, Rhythm Shimakawa, Yoichi Tamura, Tomoko L. Suzuki

Research output: Contribution to journalArticlepeer-review

33 Citations (Scopus)


We report a survey of molecular gas in galaxies in the XMMXCS J2215.9-1738 cluster at z = 1.46. We have detected emission lines from 17 galaxies within a radius of R 200 from the cluster center, in Band 3 data of the Atacama Large Millimeter/submillimeter Array, with a coverage of 93-95 GHz in frequency and 2.33 arcmin2 in spatial direction. The lines are all identified as CO J = 2-1 emission lines from cluster members at by their redshifts and the colors of their optical and near-infrared (NIR) counterparts. The line luminosities reach down to Lco(2-1) = 4.5 × 109K K km s-1 pc2. The spatial distribution of galaxies with a detection of CO(2-1) suggests that they disappear from the very center of the cluster. The phase-space diagram showing relative velocity versus cluster-centric distance indicates that the gas-rich galaxies have entered the cluster more recently than the gas-poor star-forming galaxies and passive galaxies located in the virialized region of this cluster. The results imply that the galaxies experienced ram-pressure stripping and/or strangulation during the course of infall toward the cluster center and then the molecular gas in the galaxies at the cluster center was depleted by star formation.

Original languageEnglish
Article numberL21
JournalAstrophysical Journal Letters
Issue number2
Publication statusPublished - 2017 Jun 1
Externally publishedYes


  • galaxies: ISM
  • galaxies: clusters: individual (XMMXCS J2215.91738)
  • galaxies: evolution

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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