Decoding the Milky Way Galaxy

Fri, Feb 15, 2019, 2:00 pm to 3:00 pm
Peyton Hall, Room 145
Center for Statistics and Machine Learning
Department of Astrophysical Sciences


Stars residing in the Milky Way halo hold the key to the origin of our Galaxy. The stellar halo has traditionally been inaccessible as it contains only one percent of stars in the Galaxy. However, novel data sets have enabled us to confidently identify thousands of halo stars in a high-dimensional space of stellar positions, velocities and intrinsic properties, such as chemical abundance and age. In this talk I will show how even completely dissolved progenitors of the Milky Way appear as overdensities in this space. Its structure offers an archaeological window into the early universe, and I will provide examples of statistical techniques that have the potential to deliver transformative breakthroughs in this field. Spatially coherent structures in the Milky Way halo are even more informative: a Fisher analysis indicates that they constrain the mass enclosed within their current location. I will discuss how the forward-modeling framework I developed for individual structures can be extended to build a hierarchical model for a network of such objects. This inference will reconstruct the three-dimensional distribution of the otherwise elusive dark matter in the Milky Way.


ITC Fellow Ana Bonaca studies how the tidal field of the Milky Way galaxy disrupts globular clusters, and what the resulting debris can tell us about the underlying distribution of dark matter. In her work, she uses data from large photometric surveys, as well as high-resolution numerical simulations. Ana received her PhD in Astronomy from Yale University in 2016. 

Research Interests:   Tidal disruption of Galactic satellites and buildup of its stellar halo, global mapping of dark matter in the Milky Way and searches for low-mass dark matter subhalos.