The test for suppressed dynamical friction in a constant density core of
  dwarf galaxies
  The dynamical friction problem is a long-standing dilemma about globular
clusters (hereafter,GCs) belonging to dwarf galaxies. GCs are strongly affected
by dynamical friction in dwarf galaxies, and are presumed to fall into the
galactic center. But, GCs do exist in dwarf galaxies generally. A solution of
the problem has been proposed. If dwarf galaxies have a core dark matter halo
which has constant density distribution in its center, the effect of dynamical
friction will be weakened considerably, and GCs should be able to survive
beyond the age of the universe. Then, the solution argued that, in a cored dark
halo, the suppression of dynamical friction is caused by a new equilibrium
state constructed by the interaction between the halo and the GC, in which a
part of the halo rotates along with the GC (co-rotating state). In this study,
I tested whether the solution is reasonable and reconsidered why a constant
density, core halo suppresses dynamical friction, by means of N-body
simulations. As a result, I conclude that the true mechanism of suppressed
dynamical friction is not the co-rotating state, although a core halo can
actually suppress dynamical friction on GCs significantly.
