Spatial anisotropy of galaxy kinematics in sloan digital sky survey galaxy clusters

Andreas Skielboe, Radosław Wojtak, Kristian Pedersen, Eduardo Rozo, Eli S. Rykoff

Research output: Contribution to journalArticle

15 Scopus citations

Abstract

Measurements of galaxy cluster kinematics are important in understanding the dynamical state and evolution of clusters of galaxies, as well as constraining cosmological models. While it is well established that clusters exhibit non-spherical geometries, evident in the distribution of galaxies on the sky, azimuthal variations of galaxy kinematics within clusters have yet to be observed. Here we measure the azimuthal dependence of the line-of-sight velocity dispersion profile in a stacked sample of 1743 galaxy clusters from the Sloan Digital Sky Survey (SDSS). The clusters are drawn from the SDSS DR8 redMaPPer catalog. We find that the line-of-sight velocity dispersion of galaxies lying along the major axis of the central galaxy is larger than those that lie along the minor axis. This is the first observational detection of anisotropic kinematics of galaxies in clusters. We show that the result is consistent with predictions from numerical simulations. Furthermore, we find that the degree of projected anisotropy is strongly dependent on the line-of-sight orientation of the galaxy cluster, opening new possibilities for assessing systematics in optical cluster finding.

Original languageEnglish (US)
Article numberL16
JournalAstrophysical Journal Letters
Volume758
Issue number1
DOIs
StatePublished - Oct 10 2012

Keywords

  • clusters
  • galaxies
  • general galaxies
  • kinematics and dynamics

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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