Detecting dark matter subhalos with the Nancy Grace Roman Space Telescope

Dark matter substructure is a promising way of distinguishing between dark matter models. While cold dark matter predicts halos down to quite small scales, other models typically predict a cut-off in the subhalo mass function. If these subhalos existed in the Milky Way, they would produce weak lensing signatures on background stars. These signatures would produce correlated apparent velocity and acceleration signatures, which could be observable given sufficient astrometric resolution and cadence. The Nancy Grace Roman Space Telescope's Exoplanet Microlensing Survey will be perfectly suited to looking for the acceleration signatures of these halos. Here we forward model these acceleration signatures and explore the Roman Space Telescope future constraints on lens profiles and populations. In particular, we find that the Roman Space Telescope will place strong limits on both small and large point-source halos, as well as constraints on very concentrated diffuse halos. We also discuss possible systematic effects that could hinder these efforts and methods for improving these constraints.