The Outer Halos of Very Massive Galaxies: BCGs and their DSC in the
  Magneticum Simulations
  Recent hydrodynamic cosmological simulations cover volumes up to Gpc^3 and
resolve halos across a wide range of masses and environments, from massive
galaxy clusters down to normal galaxies, while following a large variety of
physical processes (star formation, chemical enrichment, AGN feedback) to allow
a self-consistent comparison to observations at multiple wavelengths. Using the
Magneticum simulations, we investigate the buildup of the diffuse stellar
component (DSC) around massive galaxies within group and cluster environments.
The DSC in our simulations reproduces the spatial distribution of the observed
intracluster light (ICL) as well as its kinematic properties remarkably well.
For galaxy clusters and groups we find that, although the DSC in almost all
cases shows a clear separation from the brightest cluster galaxy (BCG) with
regard to its dynamic state, the radial stellar density distribution in many
halos is often characterized by a single Sersic profile, representing both the
BCG component and the DSC, very much in agreement with current observational
results. Interestingly, even in those halos that clearly show two components in
both the dynamics and the spatial distribution of the stellar component, no
correlation between them is evident.
