First Simulations of Axion Minicluster Halos
  We study the gravitational collapse of axion dark matter fluctuations in the
post-inflationary scenario, so-called axion miniclusters, with N-body
simulations. Largely confirming theoretical expectations, overdensities begin
to collapse in the radiation-dominated epoch and form an early distribution of
miniclusters with masses up to $10^{-12}\,M_\odot$. After matter-radiation
equality, ongoing mergers give rise to a steep power-law distribution of
minicluster halo masses. The density profiles of well-resolved halos are
NFW-like to good approximation. The fraction of axion dark matter in these
bound structures is $\sim 0.75$ at redshift $z=100$.
