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The Phoenix Project: the dark side of rich Galaxy clusters

Gao, L.; Navarro, J.F.; Frenk, C.S.; Jenkins, A.; Springel, V.; White, S.D.M.

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L. Gao

J.F. Navarro

V. Springel

S.D.M. White


We introduce the Phoenix Project, a set of Λ cold dark matter (CDM) simulations of the dark matter component of nine rich galaxy clusters. Each cluster is simulated at least at two different numerical resolutions. For eight of them, the highest resolution corresponds to ∼130 million particles within the virial radius, while for one this number is over one billion. We study the structure and substructure of these systems and contrast them with six galaxy-sized dark matter haloes from the Aquarius Project, simulated at comparable resolution. This comparison highlights the approximate mass invariance of CDM halo structure and substructure. We find little difference in the spherically averaged mass, pseudo-phase-space density and velocity anisotropy profiles of Aquarius and Phoenix haloes. When scaled to the virial properties of the host halo, the abundance and radial distribution of subhaloes are also very similar, despite the fact that Aquarius and Phoenix haloes differ by roughly three decades in virial mass. The most notable difference is that cluster haloes have been assembled more recently and are thus significantly less relaxed than galaxy haloes, which leads to decreased regularity, increased halo-to-halo scatter and sizable deviations from the mean trends. This accentuates the effects of the strong asphericity of individual clusters on surface density profiles, which may vary by up to a factor of 3 at a given radius, depending on projection. The high apparent concentration reported for some strong-lensing clusters might very well reflect these effects. A more recent assembly also explains why substructure in some Phoenix haloes is slightly more abundant than in Aquarius, especially in the inner regions. Resolved subhaloes nevertheless contribute only 11 ± 3 per cent of the virial mass in Phoenix clusters. Together, the Phoenix and Aquarius simulation series provide a detailed and comprehensive prediction of the CDM distribution in galaxies and clusters when the effects of baryons can be neglected.


Gao, L., Navarro, J., Frenk, C., Jenkins, A., Springel, V., & White, S. (2012). The Phoenix Project: the dark side of rich Galaxy clusters. Monthly Notices of the Royal Astronomical Society, 425(3), 2169-2186.

Journal Article Type Article
Acceptance Date Jun 20, 2012
Online Publication Date Sep 1, 2012
Publication Date Sep 1, 2012
Deposit Date Mar 4, 2013
Publicly Available Date Apr 22, 2016
Journal Monthly Notices of the Royal Astronomical Society
Print ISSN 0035-8711
Electronic ISSN 1365-2966
Publisher Royal Astronomical Society
Peer Reviewed Peer Reviewed
Volume 425
Issue 3
Pages 2169-2186


Published Journal Article (4 Mb)

Copyright Statement
This article has been accepted for publication in Monthly notices of the Royal Astronomical Society ©: 2012 The Authors Monthly Notices of the Royal Astronomical Society © 2012 RAS Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.

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