Simulating the Milky Way's Stellar Halo

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This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).Dr. Willman and her collaborators will study numerical simulations that follow the formation and evolution of the Milky Way's stellar halo. They will address two major questions: what is the origin of the stellar halo (is it composed of the remains of dwarf galaxies that merged into the Milky Way?) and, how typical is the Milky Way as a galaxy? The team has already performed high-resolution simulations of the formation of eight galaxies resembling our Milky Way. These incorporate physical processes including the gas dynamics, and can resolve dark halos with circular speeds of only 10-20km/s. The model will make predictions for the motions and chemical composition of the halo stars, comparing the properties of stars that were formed in the halo with those formed in smaller satellite galaxies that subsequently merged with the central galaxy. The results from these simulations will be compared to observations of the Milky Way's stellar halo from the large Sloan Digital Sky Survey.Thus award will support the thesis project of a female graduate student. Dr Willman will develop a computational lab based on this research for her advanced undergraduate classes, and for dissemination on her website. Predictions from this project will facilitate the interpretation of data from future large surveys of stars in the halo of the Milky Way and nearby galaxies.