  We have proposed a model of a progenitor of fast radio bursts (FRBs): The
FRBs are emitted by electrons in atmospheres of neutron stars when neutron
stars collide with dark matter axion stars. We reexamine the model by taking
account of the tidal forces of the neutron stars. The axion stars are distorted
by the forces so that they become like long sticks when they are close to the
neutron stars. Although the tidal forces fairly distort the axion stars, our
model is still consistent with present observations. We explain a distinctive
feature of our model that the FRBs are not broadband, but narrowband. We also
show that two-component FRBs may arise when the axion stars collide with binary
neutron stars. FRBs would most frequently arise in centers of galaxies since
the dark matter concentrates in the centers.
