On the possibility of Bose-star formation

The relaxation time of a gravitationally bounded cloud of bosons is estimated for the case of a large phase-space density of particles. The axionic mass and self-coupling relaxation time are compatible to the age of the Universe if the escape velocity and the mass in the core region satisfy the relation M<108νe5/2f10-1/4Msun. In the central part of such a cloud an axionic cosmic matter with luminosity ≅ 10-2νr5/2f10-1/4Msun/yr will form. An upper bound on the self-coupling is obtained provided the mass distribution in galaxies is dominated by this kind of dark matter. (orig.)