The structure of the merging RCS 231953+00 supercluster at z ~ 0.9

A. J. Faloon, T. M. A. Webb, E. Ellingson, R. Yan, David G. Gilbank, J. E. Geach, A. G. Noble, L. F. Barrientos, H. K. C. Yee, M. Gladders, J. Richard

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Abstract

The RCS2319+00 supercluster is a massive supercluster at z = 0.9 comprising three optically selected, spectroscopically confirmed clusters separated by <3Mpc on the plane of the sky. This supercluster is one of a few known examples of the progenitors of present-day massive clusters (1015 M ☉ by z ~ 0.5). We present an extensive spectroscopic campaign carried out on the supercluster field resulting, in conjunction with previously published data, in 1961 high-confidence galaxy redshifts. We find 302 structure members spanning three distinct redshift walls separated from one another by ~65Mpc (Δ z = 0.03). The component clusters have spectroscopic redshifts of 0.901, 0.905, and 0.905. The velocity dispersions are consistent with those predicted from X-ray data, giving estimated cluster masses of ~10 14.5-10 14.9 M ☉. The Dressler-Shectman test finds evidence of substructure in the supercluster field and a friends-of-friends analysis identified five groups in the supercluster, including a filamentary structure stretching between two cluster cores previously identified in the infrared by Coppin etal. The galaxy colors further show this filamentary structure to be a unique region of activity within the supercluster, comprised mainly of blue galaxies compared to the ~43%-77% red-sequence galaxies present in the other groups and cluster cores. Richness estimates from stacked luminosity function fits result in average group mass estimates consistent with ~1013 M ☉ halos. Currently, 22% of our confirmed members reside in 1013 M ☉ groups/clusters destined to merge onto the most massive cluster, in agreement with the massive halo galaxy fractions important in cluster galaxy pre-processing in N-body simulation merger tree studies

Original languageEnglish
Article number104
Number of pages21
JournalThe Astrophysical Journal
Volume768
Issue number2
DOIs
Publication statusPublished - 10 May 2013

Keywords

  • RICH CLUSTERS
  • SEQUENCE CLUSTER SURVEY
  • SDSS DR7 SUPERCLUSTERS
  • REDSHIFT SURVEY
  • CL-1604 SUPERCLUSTER
  • COLOR-MAGNITUDE RELATION
  • techniques: spectroscopic
  • GALAXY CLUSTERS
  • galaxies: clusters: individual (RCS 231953+0038.0, RCS 232002+0033.4, RCS 231948+0030.1)
  • LUMINOSITY FUNCTION
  • galaxies: high-redshift
  • DIGITAL SKY SURVEY
  • RED-SEQUENCE

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