The Milky Way as the frontier laboratory for cosmology

Almost all stars that our eyes can see in the night sky belong to our Galaxy, the Milky Way. Hidden in their motions are clues to the cosmic origins of galaxies and the nature of the elusive dark matter, the invisible matter permeating the entire universe, detected only through gravity. Unlike in any other galaxy, precise positions and motions of these stars are being measured by large teams of British and European scientists.

My goal is to measure orbits of stars and create matching theoretical models to learn where they come from and what they encountered on their journey.

In these experiments, my main test subjects will be stellar streams: groups of stars moving along similar orbits around the Milky Way. Using new measurements of stellar velocities, I will calculate orbits for dozens of these streams and identify which of them are related, thus building the family tree of our Galaxy. Shaped by gravitational forces, stellar streams are also great for detecting dark matter.

Competing theoretical models of dark matter predict different amounts of small dark-matter clumps populating a galaxy like the Milky Way. Clumps of dark matter would punch holes through stellar streams, and I will first look for signatures of such perturbations throughout the Milky Way, and then estimate the number of clumps necessary to match the observed amount of perturbation.

Ultimately, my findings will help answer the fundamental questions of cosmology: What is the universe made of and how did it come to be?