%0 Journal Article
%T Axion Miniclusters and Bose Stars
%A Edward W. Kolb
%A Igor I. Tkachev
%J Physics
%D 1993
%I arXiv
%R 10.1103/PhysRevLett.71.3051
%X Evolution of inhomogeneities in the axion field around the QCD epoch is studied numerically, including for the first time important non-linear effects. It is found that perturbations on scales corresponding to causally disconnected regions at $T \sim 1 \, {\rm GeV}$ can lead to very dense axion clumps, with present density $\rho_a \ga 10^{-8}\,{\rm g \, cm^{-3}}$. This is high enough for the collisional $2a \rightarrow 2a$ process to lead to Bose--Einstein relaxation in the gravitationally bound clumps of axions, forming Bose stars.
%U http://arxiv.org/abs/hep-ph/9303313v1