Cosmology and Astrophysics from Relaxed Galaxy Clusters V: Consistency
  with Cold Dark Matter Structure Formation
  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 $\kappa_m=-0.16\pm0.07$, 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
$\kappa_\zeta=-0.17\pm0.26$), with an intrinsic scatter of $\sigma_{\ln
c}=0.16\pm0.03$. We investigate the shape of cluster mass profiles over the
radial range probed by the data (typically $\sim50$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 $\beta=1.02\pm0.08$, with an intrinsic
scatter of $\sigma_\beta=0.22\pm0.07$, while in the Einasto case we constrain
the average shape parameter to be $\alpha=0.29\pm0.04$ with an intrinsic
scatter of $\sigma_\alpha=0.12\pm0.04$. 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.
