Skip to main content

Research Repository

Advanced Search

The effect of baryons on the inner density profiles of rich clusters

Schaller, Matthieu; Frenk, Carlos S.; Bower, Richard G.; Theuns, Tom; Trayford, James W.; Crain, Robert A.; Furlong, Michelle; Schaye, Joop; Dalla Vecchia, Claudio; McCarthy, Ian G.

The effect of baryons on the inner density profiles of rich clusters Thumbnail


Richard G. Bower

James W. Trayford

Robert A. Crain

Michelle Furlong

Joop Schaye

Claudio Dalla Vecchia

Ian G. McCarthy


We use the ‘Evolution and assembly of galaxies and their environments’ (EAGLE) cosmological simulation to investigate the effect of baryons on the density profiles of rich galaxy clusters. We focus on EAGLE clusters with M200 > 1014 M⊙ of which we have six examples. The central brightest cluster galaxies (BCGs) in the simulation have steep stellar density profiles, ρ*(r) ∝ r−3. Stars dominate the mass density for r < 10 kpc, and, as a result, the total mass density profiles are steeper than the Navarro–Frenk–White (NFW) profile, in remarkable agreement with observations. The dark matter halo itself closely follows the NFW form at all resolved radii (r ≳ 3.0 kpc). The EAGLE BCGs have similar surface brightness and line-of-sight velocity dispersion profiles as the BCGs in the sample of Newman et al., which have the most detailed measurements currently available. After subtracting the contribution of the stars to the central density, Newman et al. infer significantly shallower slopes than the NFW value, in contradiction with the EAGLE results. We discuss possible reasons for this discrepancy, and conclude that an inconsistency between the kinematical model adopted by Newman et al. for their BCGs, which assumes isotropic stellar orbits, and the kinematical structure of the EAGLE BCGs, in which the orbital stellar anisotropy varies with radius and tends to be radially biased, could explain at least part of the discrepancy.


Schaller, M., Frenk, C. S., Bower, R. G., Theuns, T., Trayford, J. W., Crain, R. A., …McCarthy, I. G. (2015). The effect of baryons on the inner density profiles of rich clusters. Monthly Notices of the Royal Astronomical Society, 452(1), 343-355.

Journal Article Type Article
Acceptance Date Jun 14, 2015
Publication Date Sep 1, 2015
Deposit Date Oct 22, 2015
Publicly Available Date Nov 5, 2015
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 452
Issue 1
Pages 343-355
Keywords Galaxies: clusters: general, Galaxies: haloes, Cosmology: theory, Dark matter.
Related Public URLs


Published Journal Article (1.8 Mb)

Copyright Statement
This article has been accepted for publication in Monthly notices of the Royal Astronomical Society. ©: 2015 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.

You might also like

Downloadable Citations