Mass profile decomposition of the Frontier Fields cluster MACS
  J0416-02403. Insights on the Dark-Matter inner profile
  We present a high resolution dissection of the two-dimensional total mass
distribution in the core of the Hubble Frontier Fields galaxy cluster MACS
J0416.1-2403, at z ~ 0.396. We exploit HST/WFC3 near-IR (F160W) imaging,
VLT/MUSE spectroscopy, and Chandra data to separate the stellar, hot gas, and
dark-matter mass components in the inner 300 kpc of the cluster. We combine the
recent results of our refined strong lensing analysis, which includes the
contribution of the intracluster gas, with the modeling of the surface
brightness and stellar mass distributions of 193 cluster members, of which 144
are spectroscopically confirmed. We find that moving from 10 to 300 kpc from
the cluster center the stellar to total mass fraction decreases from 12% to 1%
and the hot gas to total mass fraction increases from 3% to 9%, resulting in a
baryon fraction of approximately 10% at the outermost radius. We measure that
the stellar component represents ~ 30%, near the cluster center, and 15%, at
larger clustercentric distances, of the total mass in the cluster
substructures. We subtract the baryonic mass component from the total mass
distribution and conclude that within 30 kpc (~ 3 times the effective radius of
the BCG) from the cluster center the surface mass density profile of the total
mass and global (cluster plus substructures) dark-matter are steeper and that
of the diffuse (cluster) dark-matter is shallower than a NFW profile. Our
current analysis does not point to a significant offset between the cluster
stellar and dark-matter components. This detailed and robust reconstruction of
the inner dark-matter distribution in a larger sample of galaxy clusters will
set a new benchmark for different structure formation scenarios.
