XMM-Newton study of the two-dimensional structure of the REFLEX-DXL galaxy clusters

Free access article

Issue		A&A Volume 442, Number 3, November II 2005


Page(s)		827 - 839
Section		Cosmology (including clusters of galaxies)
DOI		http://dx.doi.org/10.1051/0004-6361:20053306

A&A 442, 827-839 (2005)
DOI: 10.1051/0004-6361:20053306

XMM-Newton study of the two-dimensional structure of the REFLEX-DXL galaxy clusters

A. Finoguenov, H. Böhringer and Y.-Y. Zhang

Max-Planck-Institut für extraterrestrische Physik, Giessenbachstraße, 85748 Garching, Germany
e-mail: alexis@xray.mpe.mpg.de

(Received 25 April 2005 / Accepted 20 June 2005 )

Abstract
We carry out a two-dimensional study of temperature, entropy, and pressure distributions in a nearly volume-limited subsample of REFLEX clusters at redshift 0.3, the REFLEX-DXL. We use the observations gained by XMM-Newton, which cover the central $1{-}2\times r_{500}$ . We define the substructure in both entropy and pressure as a deviation from the mean profile of the sample. The non-parametric locally weighted regression suggests a broken power-law approximation to the entropy profile with inner and outer slopes of 0.78 and 0.52, respectively, and a break at 0.5r₅₀₀. Characterization of the pressure profile is more complex, requiring three power laws, with slopes -0.64 at r<0.3r₅₀₀, -2.47 at r>0.5r₅₀₀ and a slope of -1.50 in between. Analysis of the substructure in the pressure and entropy maps reveals somewhat larger fluctuations around the mean pressure profile compared to the entropy. Typically, pressure fluctuations are found at the 30% level, while the entropy fluctuations are at the 20% level (rms). We compare the cumulative distribution of the substructure level in the REFLEX-DXL sample with the results of numerical simulation, and by means of KS test, show that they are in agreement. A discussion of the origin of the substructure is provided on an individual cluster basis.

Key words: cosmology: observations -- galaxies: clusters: general

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