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

Research output: Contribution to journalArticlepeer-review

9 Scopus citations

Abstract

The RCS 2319+00 supercluster is a massive supercluster at z = 0.9 comprising three optically selected, spectroscopically confirmed clusters separated by <3 Mpc on the plane of the sky. This supercluster is one of a few known examples of the progenitors of present-day massive clusters (10 15 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 ∼65 Mpc (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 ∼1014.5-1014.9 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 et al. 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 (US)
Article number104
JournalAstrophysical Journal
Volume768
Issue number2
DOIs
StatePublished - May 10 2013
Externally publishedYes

Keywords

  • galaxies: high-redshift
  • techniques: spectroscopic

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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