case western reserve university



Mapping the Local Group

Kathryn Johnston (Columbia)

In the last decade, the stellar halos of the Milky Way and Andromeda galaxies have been mapped in exquisite detail, revealing abundant substructure and many new satellites. These observations are qualitatively consistent with our expectations for large galaxies formed hierarchically from smaller galaxies, but are they actually telling us anything more quantifiable? In this talk I will review the origin of these substructures, discuss how they can be mapped and discuss possible interpretations.