Journal Article

Richness dependence of the recent evolution of clusters of galaxies

Manolis Plionis, Hrant M. Tovmassian and Heinz Andernach

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 395, issue 1, pages 2-10
Published in print May 2009 | ISSN: 0035-8711
Published online April 2009 | e-ISSN: 1365-2966 | DOI:
Richness dependence of the recent evolution of clusters of galaxies

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We revisit the issue of the recent dynamical evolution of clusters of galaxies using a sample of Abell, Corwin & Olowin (ACO) clusters with z < 0.14, which has been selected such that it does not contain clusters with multiple velocity components nor strongly merging or interacting clusters, as revealed in X-rays. We use as proxies of the cluster dynamical state the projected cluster ellipticity, velocity dispersion and X-ray luminosity. We find indications for a recent dynamical evolution of this cluster population, which however strongly depends on the cluster richness. Poor clusters appear to be undergoing their primary phase of virialization, with their ellipticity increasing with redshift with a rate dε/dz≃ 2.5 ± 0.4, while the richest clusters show an ellipticity evolution in the opposite direction (with dε/dz≃−1.2 ± 0.1), which could be due to secondary infall. When taking into account sampling effects due to the magnitude-limited nature of the ACO cluster catalogue we find no significant evolution of the cluster X-ray luminosity, while the velocity dispersion increases with decreasing redshift, independent of the cluster richness, at a rate dσv/dz≃−1700 ± 400 km s−1.

Keywords: galaxies: clusters: general; galaxies: evolution

Journal Article.  5878 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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