The MUSIC of CLASH: predictions on the concentration-mass relation
  We present the results of a numerical study based on the analysis of the
MUSIC-2 simulations, aimed at estimating the expected concentration-mass
relation for the CLASH cluster sample. We study nearly 1400 halos simulated at
high spatial and mass resolution, which were projected along many
lines-of-sight each. We study the shape of both their density and
surface-density profiles and fit them with a variety of radial functions,
including the Navarro-Frenk-White, the generalised Navarro-Frenk-White, and the
Einasto density profiles. We derive concentrations and masses from these fits
and investigate their distributions as a function of redshift and halo
relaxation. We use the X-ray image simulator X-MAS to produce simulated Chandra
observations of the halos and we use them to identify objects resembling the
X-ray morphologies and masses of the clusters in the CLASH X-ray selected
sample. We also derive a concentration-mass relation for strong-lensing
clusters. We find that the sample of simulated halos which resemble the X-ray
morphology of the CLASH clusters is composed mainly by relaxed halos, but it
also contains a significant fraction of un-relaxed systems. For such a sample
we measure an average 2D concentration which is ~11% higher than found for the
full sample of simulated halos. After accounting for projection and selection
effects, the average NFW concentrations of CLASH clusters are expected to be
intermediate between those predicted in 3D for relaxed and super-relaxed halos.
Matching the simulations to the individual CLASH clusters on the basis of the
X-ray morphology, we expect that the NFW concentrations recovered from the
lensing analysis of the CLASH clusters are in the range [3-6], with an average
value of 3.87 and a standard deviation of 0.61. Simulated halos with X-ray
morphologies similar to those of the CLASH clusters are affected by a modest
orientation bias.
