Relativistic collapse of axion stars
  We study the gravitational collapse of an axion field in null coordinates,
assuming spherical symmetry. Compared with previous studies, we use a simpler
numerical scheme which can run, for relevant parameters, in a few minutes or
less on a desktop computer. We use it to accurately determine the domains of
parameter space in which the axion field forms a black hole, an axion star or a
relativistic Bosenova.
