Speaker
Description
Axion stars are condensed states of large numbers of axion particles, bound by self-gravitation and attractive self-interactions. Such states generically arise in theories of light scalars, where the critical temperature for the transition is very high. By solving the semiclassical equations of motion, we find the maximum gravitationally stable mass for weakly bound axion stars. Further, the Hermiticity of the axion field leads to number-changing processes in the axion potential, and consequently a finite lifetime for axion stars which bounds their masses from below. These bounds taken together, along with astrophysical constraints on the mass of QCD axions, constrain significantly the allowed parameter space for axion stars. The consequences for axionic dark matter will also be discussed.
