Constraining the inner density slope of massive galaxy clusters
  We determine the inner density profiles of massive galaxy clusters (M$_{200}$
> $5 \times 10^{14}$ M$_{\odot}$) in the Cluster-EAGLE (C-EAGLE) hydrodynamic
simulations, and investigate whether the dark matter density profiles can be
correctly estimated from a combination of mock stellar kinematical and
gravitational lensing data. From fitting mock stellar kinematics and lensing
data generated from the simulations, we find that the inner density slopes of
both the total and the dark matter mass distributions can be inferred
reasonably well. We compare the density slopes of C-EAGLE clusters with those
derived by Newman et al. for 7 massive galaxy clusters in the local Universe.
We find that the asymptotic best-fit inner slopes of "generalized" NFW (gNFW)
profiles, ${\gamma}_{\rm gNFW}$, of the dark matter haloes of the C-EAGLE
clusters are significantly steeper than those inferred by Newman et al.
However, the mean mass-weighted dark matter density slopes of the simulated
clusters are in good agreement with the Newman et al. estimates. We also find
that the estimate of ${\gamma}_{\rm gNFW}$ is very sensitive to the constraints
from weak lensing measurements in the outer parts of the cluster and a bias can
lead to an underestimate of ${\gamma}_{\rm gNFW}$.
