A technique for detecting structure in cluster velocity distributions

Ann I Zabludoff, Marijn Franx, Margaret J. Geller

Research output: Contribution to journalArticle

24 Scopus citations

Abstract

For clusters with ≳ 100 measured galaxy redshifts, we develop a new method for detecting departures from a Gaussian velocity distribution. We decompose the cluster velocity distribution into a sum of the orthogonal Gauss-Hermite functions. This method quantifies the asymmetric third-order (h3) and symmetric fourth-order (h4) terms of the distribution while minimizing the effect of interlopers in the tails. We apply the method to a sample of eight rich clusters: A426, A548, A1060, A1656, A2151, A2670, DC 2048-52, and Centaurus. Each cluster has more than 100 members with known redshifts. The clusters A548, A1656, DC 2048-52, and Centaurus significantly depart from Gaussian. A1656 and DC 2048-52 have asymmetric velocity distributions; A548 and Centaurus have broad, symmetric distributions. The most likely interpretation is that these systems have substructure. This result is consistent with findings by other authors.

Original languageEnglish (US)
Pages (from-to)47-51
Number of pages5
JournalAstrophysical Journal
Volume419
Issue number1
Publication statusPublished - Dec 10 1993
Externally publishedYes

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Keywords

  • Galaxies: clustering
  • Galaxies: distances and redshifts

ASJC Scopus subject areas

  • Space and Planetary Science

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