First Results on Dark Matter Substructure from Astrometric Weak Lensing

Understand

Low-mass structures of dark matter (DM) are expected to be entirely devoid of light-emitting regions and baryons.

• Precisely because of this lack of baryonic feedback, small-scale substructures of the Milky Way are a relatively pristine testing ground for discovering aspects of DM microphysics and primordial fluctuations on subgalactic scales.
• In this work, we report results from the first search for Galactic DM subhalos with time-domain astrometric weak gravitational lensing.
• The analysis is based on a matched-filter template of local lensing corrections to the proper motion of stars in the Magellanic Clouds.