Axion Stars and Fast Radio Bursts

We show that fast radio bursts arise from collisions between axion stars and neutron stars. The bursts are emitted in the atmosphere of the neutron stars. The observed frequencies of the bursts are given by the axion mass $m_a$ such as $m_a/2\pi\simeq 1.4\,\mbox{GHz}\,\big(m_a/(6\times 10^{-6}\mbox{eV})\big)$. From the event rate $\sim 10^{-3}$ per year in a galaxy, we can determine the mass $\sim 10^{-11}M_{\odot}$ of the axion stars. Using these values we can explain short durations ( $\sim $ms ) and amount of radiation energies ( $\sim 10^{43}$GeV ) of the bursts.