Relaxation times for Bose-Einstein condensation in axion miniclusters
  We study the Bose condensation of scalar dark matter in the presence of both
gravitational and self-interactions. Axions and other scalar dark matter in
gravitationally bound miniclusters or dark matter halos are expected to
condense into Bose-Einstein condensates called Bose stars. This process has
been shown to occur through attractive self-interactions of the axion-like
particles or through the field's self gravitation. We show that in the
high-occupancy regime of scalar dark matter, the Boltzmann collision integral
does not describe either gravitaitonal or self-interactions, and derive kinetic
equations valid for these interactions. We use this formalism to compute
relaxation times for the Bose-Einstein condensation, and find that condensation
into Bose stars could occur within the lifetime of the universe. The
self-interactions reduce the condensation time only when they are very strong.
