  Collapsing collisionless particle systems form gravitational bound halos with
cuspy density profiles. Also hierarchical merging of these systems produce
remnants with cuspy central density profiles. These results lead to the
assumption of cuspy NFW profiles for the density distribution in dark matter
halos. However, observed rotation curves in disk galaxies suggest dark matter
halos with isothermal core. The same kind of problem can be found for globular
clusters, which show cores in their density profiles but should be cuspy if
they where formed through a cold collapse.We are showing how small, massive,
and compact objects can efficiently transform cuspy stellar systems into
density profiles with an isothermal core.
