Gravitational Microlensing Rates in Milky Way Globular Clusters
  Many recent observational and theoretical studies suggest that globular
clusters (GCs) host compact object populations large enough to play dominant
roles in their overall dynamical evolution. Yet direct detection, particularly
of black holes and neutron stars, remains rare and limited to special cases,
such as when these objects reside in close binaries with bright companions.
Here we examine the potential of microlensing detections to further constrain
these dark populations. Based on state-of-the-art GC models from the CMC
Cluster Catalog, we estimate the microlensing event rates for black holes,
neutron stars, white dwarfs, and, for comparison, also for M dwarfs in Milky
Way GCs, as well as the effects of different initial conditions on these rates.
Among compact objects, we find that white dwarfs dominate the microlensing
rates, simply because they largely dominate by numbers. We show that
microlensing detections are in general more likely in GCs with higher initial
densities, especially in clusters that undergo core collapse. We also estimate
microlensing rates in the specific cases of M22 and 47 Tuc using our
best-fitting models for these GCs. Because their positions on the sky lie near
the rich stellar backgrounds of the Galactic bulge and the Small Magellanic
Cloud, respectively, these clusters are among the Galactic GCs best-suited for
dedicated microlensing surveys. The upcoming 10-year survey with the Rubin
Observatory may be ideal for detecting lensing events in GCs.
