Dark Matter Mass Fraction in Axion Stars

Axion dark matter arises naturally in Quantum Chromodynamics and fragments into low-mass, high-density mini-clusters early in the evolution of the Universe. With the natural parameters of miniclusters, the time for Bose–Einstein condensation is less than the age of the Universe, which leads to the formation of Bose stars inside these structures. Recently, the problem of the subsequent growth of Bose stars was solved analytically (Dmitriev et al, Phys. Rev. Lett. 132, 091001 (2024)). We use this solution to determine present day mass fraction of dark matter in Bose stars and their mass function.