The Density Profiles of Massive, Relaxed Galaxy Clusters. II. Separating
  Luminous and Dark Matter in Cluster Cores
  We present stellar and dark matter (DM) density profiles for a sample of
seven massive, relaxed galaxy clusters derived from strong and weak
gravitational lensing and resolved stellar kinematic observations within the
centrally-located brightest cluster galaxies (BCGs). In Paper I of the series,
we demonstrated that the total density profile derived from these data, which
span 3 decades in radius, is consistent with numerical DM-only simulations at
radii >~ 5-10 kpc, despite the significant contribution of stellar material in
the core. Here we decompose the inner mass profiles of these clusters into
stellar and dark components. Parametrizing the DM density profile as a power
law rho_DM ~ r^{-\beta} on small scales, we find a mean slope <\beta> = 0.50 +-
0.10 (random) +0.14-0.13 (systematic). Alternatively, cored Navarro-Frenk-White
(NFW) profiles with <log r_core/kpc> = 1.14 +- 0.13 (random) +0.14-0.22
(systematic) provide an equally good description. These density profiles are
significantly shallower than canonical NFW models at radii <~ 30 kpc,
comparable to the effective radii of the BCGs. The inner DM profile is
correlated with the distribution of stars in the BCG, suggesting a connection
between the inner halo and the assembly of stars in the central galaxy. The
stellar mass-to-light ratio inferred from lensing and stellar dynamics is
consistent with that inferred using stellar population synthesis models if a
Salpeter initial mass function is adopted. We compare these results to theories
describing the interaction between baryons and DM in cluster cores, including
adiabatic contraction models and the possible effects of galaxy mergers and
active galactic nucleus feedback, and evaluate possible signatures of
alternative DM candidates.
