Timescale of axion condensation in miniclusters

Axions and other scalar dark matter in gravitationally bound miniclusters are expected to condense into solitons, which are in the Bose-Einstein condensate phase. This process has been shown to occur either through attractive self-interactions of the axion-like particles or through the field's self gravitation. We derive kinetic equations valid for both these interactions in the high-occupancy regime of scalar dark matter. 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.