Gravitational Microlensing by Neutron Stars and Radio Pulsars: Event
  Rates, Timescale Distributions, and Mass Measurements
  We investigate properties of Galactic microlensing events in which a stellar
object is lensed by a neutron star. For an all-sky photometric microlensing
survey, we determine the number of lensing events caused by $\sim10^{5}$
potentially-observable radio pulsars to be $\sim0.2\ \rm{yr^{-1}}$ for
$10^{10}$ background stellar sources. We expect a few detectable events per
year for the same number of background sources from an astrometric microlensing
survey. We show that such a study could lead to precise measurements of radio
pulsar masses. For instance, if a pulsar distance could be constrained through
radio observations, then its mass would be determined with a precision of
$\sim10\%$. We also investigate the time-scale distributions for neutron star
events, finding that they are much shorter than had been previously thought.
For photometric events towards the Galactic centre that last $\sim15$ days,
around $7\%$ will have a neutron star lens. This fraction drops rapidly for
longer time-scales. Away from the bulge region we find that neutron stars will
contribute $\sim40\%$ of the events that last less than $\sim10$ days. These
results are in contrast to earlier work which found that the maximum fraction
of neutron star events would occur on time-scales of hundreds of days.
