Kicked Neutron Stars and Microlensing

Due to the large kick velocities with which neutron stars are born insupernovae explosions, their spatial distribution is more extended than that oftheir progenitor stars. The large scale height of the neutron stars above thedisk plane makes them potential candidates for microlensing of stars in theLarge Magellanic Cloud. Adopting for the distribution of kicks the measuredvelocities of young pulsars, we obtain a microlensing optical depth of $\tau\sim 2 N_{10} \times 10^{-8}$ (where $N_{10}$ is the total number of neutronstars born in the disk in units of $10^{10}$). The event duration distributionhas the interesting property of being peaked at $T \sim 60$--80 d, but for therates to be relevant for the present microlensing searches would require$N_{10} \gtap 1$, a value larger than the usually adopted ones ($N_{10} \sim0.1$--0.2).Comment: latex, 10 p. + 2 fig