Event

The Gaia astrometric survey has delivered a detailed “close-up” of our Galaxy, the Milky Way, by measuring precise 3D positions and velocities for over a billion stars. This view has upended plans for a new era of “precision Galactic dynamics.” Rather than a quasi-equilibrium system neatly described by existing theoretical models and representative of other galaxies of similar mass, we are confronted instead with an imperfect Rosetta Stone: a Galaxy that is significantly out of equilibrium, strongly influenced by its neighbors and environment, and an evident outlier among its supposed peers. Over the past several years, I have shown that these findings call into question many of the fundamental assumptions long used to infer our Galaxy's properties and draw generalized conclusions from them. Nevertheless, I contend that the Milky Way is still the best laboratory for detailed studies of astrophysical dark matter and galaxy formation, and have developed new theoretical and computational tools that can turn these challenges into opportunities. Our Galaxy's unusual features, revealed by Gaia's “close-up,” now argue for a “wide-angle” view that places the Milky Way in the context of nearby galaxies. I show that confronting observations of nearby galaxies by next-generation telescopes with synthetic observations that model both wide-angle and close-up views will harness our exquisitely detailed picture of Milky Way dynamics to realize the promise of near-field cosmology.