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The Evolving Shape of Galaxy Clusters

Published online by Cambridge University Press:  12 October 2016

Dennis W. Just ,
H. K. C. Yee ,
Adam Muzzin ,
Gillian Wilson ,
David G. Gilbank  and
Michael Gladders
Dennis W. Just
Affiliation:
Department of Astronomy and Astrophysics, University of Toronto, 50 St. George St., Toronto, ON, M5S 3H4, Canada email: dwjust@gmail.com
H. K. C. Yee
Affiliation:
Department of Astronomy and Astrophysics, University of Toronto, 50 St. George St., Toronto, ON, M5S 3H4, Canada email: dwjust@gmail.com
Adam Muzzin
Affiliation:
Leiden Observatory, Leiden University, P.O. Box 9513, 2300 RA Leiden, The Netherlands email: muzzin@strw.leidenuniv.nl
Gillian Wilson
Affiliation:
Department of Physics and Astronomy, University of California, Riverside, Pierce Hall, Riverside, CA 92521, USA email: gillian.wilson@ucr.edu
David G. Gilbank
Affiliation:
South African Astronomical Observatory, PO Box 9, 7935, South Africa email: gilbank@saao.ac.za
Michael Gladders
Affiliation:
The Department of Astronomy and Astrophysics, and the Kavli Institute for Cosmological Physics, The University of Chicago5640 South Ellis Avenue, Chicago, IL 60637, USA email: gladders@oddjob.uchicago.edu
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Abstract

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We present the first measurement of the evolution of the apparent projected shape of galaxy clusters from 0.2≲ z≲2. We measure the ellipticities (εcl) of homogeneously selected galaxy clusters over this wide redshift range. We confirm the predictions of N-body simulations that clusters are more elongated at higher redshift, finding the mean projected ellipticity changes linearly from 0.36±0.01 to 0.25±0.01 over that range. The fraction of relaxed clusters (defined as having εcl<0.2) is 9+5-3% at z∼1.8, steadily increasing to 42+7-6% by z∼0.3. Because more spherical clusters have a higher degree of virialization, our result shows significant evolution in the degree of cluster virialization over cosmic time.

Keywords

galaxies: clusters: general
Type
Contributed Papers
Information
Proceedings of the International Astronomical Union , Volume 11 , Symposium S308: The Zeldovich Universe: Genesis and Growth of the Cosmic Web , June 2014 , pp. 217 - 218
Copyright
Copyright © International Astronomical Union 2016 

References

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