Cosmology and Astrophysics from Relaxed Galaxy Clusters V: Consistency with Cold Dark Matter Structure Formation

Adam B. Mantz; Steven W. Allen; R. Glenn Morris

doi:10.1093/mnras/stw1707

paper

Cosmology and Astrophysics from Relaxed Galaxy Clusters V: Consistency with Cold Dark Matter Structure Formation

arXiv:1607.04686 · doi:10.1093/mnras/stw1707

Abstract

This is the fifth in a series of papers studying the astrophysics and cosmology of massive, dynamically relaxed galaxy clusters. Our sample comprises 40 clusters identified as being dynamically relaxed and hot in Papers I and II of this series. Here we use constraints on cluster mass profiles from X-ray data to test some of the basic predictions of cosmological structure formation in the Cold Dark Matter (CDM) paradigm. We present constraints on the concentration--mass relation for massive clusters, finding a power-law mass dependence with a slope of $κ_{m} = - 0.16 \pm 0.07$ , in agreement with CDM predictions. For this relaxed sample, the relation is consistent with a constant as a function of redshift (power-law slope with $1 + z$ of $κ_{ζ} = - 0.17 \pm 0.26$ ), with an intrinsic scatter of $σ_{l n c} = 0.16 \pm 0.03$ . We investigate the shape of cluster mass profiles over the radial range probed by the data (typically $\sim 50$ kpc--1Mpc), and test for departures from the simple Navarro, Frenk & White (NFW) form, for which the logarithmic slope of the density profile tends to $- 1$ at small radii. Specifically, we consider as alternatives the generalized NFW (GNFW) and Einasto parametrizations. For the GNFW model, we find an average value of (minus) the logarithmic inner slope of $β = 1.02 \pm 0.08$ , with an intrinsic scatter of $σ_{β} = 0.22 \pm 0.07$ , while in the Einasto case we constrain the average shape parameter to be $α = 0.29 \pm 0.04$ with an intrinsic scatter of $σ_{α} = 0.12 \pm 0.04$ . Our results are thus consistent with the simple NFW model on average, but we clearly detect the presence of intrinsic, cluster-to-cluster scatter about the average.

arXiv comment8 pages, to appear in MNRAS. Minor typos corrected in v2

Cosmology and Astrophysics from Relaxed Galaxy Clusters V: Consistency with Cold Dark Matter Structure Formation

Abstract

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