Title:
Diffuse light and galaxy interactions in the core of nearby clusters

Abstract:
The kinematics of the diffuse light in the densest regions of the
nearby clusters can be unmasked using the planetary nebulae (PNs) as
probes of the stellar motions. The position-velocity diagrams around
the brightest cluster galaxies (BCGs) identify the relative
contributions from the outer halos and the intracluster light (ICL),
defined as the light radiated by the stars floating in the cluster
potential.  The kinematics of the ICL can then be used to asses the
dynamical status of the nearby cluster cores and to infer their
formation histories. The cores of the Virgo and Coma are observed to
be far from equilibrium, with mergers currently on-going, while the
ICL properties in the Fornax and Hydra clusters show the presence of
sub-components being accreted in their cores, but superposed to an
otherwise relaxed population of stars. Finally the comparison of the
observed ICL properties with those predicted from $\Lambda$ CDM
simulations indicates a qualitative agreement and provides insights on
the ICL formation. Both observations and simulations indicate that
BCGs halos and ICL are physically distinct components, with the
``hotter" ICL dominating at large radial distances from the BCGs halos
as the latter become progressively fainter.