Nonextensive Effects on Chandrasekhar's Dynamical Friction
  The motion of a point like object of mass M passing through the background
potential of massive collisionless particles (m << M) suffers a steady
deceleration named dynamic friction. In his classical work, Chandrasekhar
assumed a Maxwellian velocity distribution in the halo and neglected the self
gravity of the wake induced by the gravitational focusing of the mass M. In
this paper, by relaxing the validity of the Maxwellian distribution due to the
presence of long range forces, we derive an analytical formula for the dynamic
friction in the context of the q-nonextensive kinetic theory. In the extensive
limiting case (q = 1), the classical Gaussian Chandrasekhar result is
recovered. As an application, the dynamic friction timescale for Globular
Clusters spiraling to the galactic center is explicitly obtained. Our results
suggest that the problem concerning the large timescale as derived by numerical
N-body simulations or semi-analytical models can be understood as a departure
from the standard extensive Maxwellian regime as measured by the Tsallis
nonextensive q-parameter.
