Schedule Feb 17, 2012
Chemical Abundance Patterns and the Early Environment of Dwarf Galaxies
Lauren Corlies (Columbia Univ.)

Recent observations have revealed that abundance differences exist between low metallicity stars in the Milky Way stellar halo and those in the ultrafaint dwarf galaxies. We take a first look at what role the early environment for pre-galactic star formation might have played in shaping these stellar populations. In particular, we consider whether differences in cross-pollution between the progenitors of the stellar halo and the ultra- faints could help to explain the differences in abundance patterns. Using an N-body simulation, we find that the progenitor halos of the main halo are primarily clustered together at z = 10 while the progenitors of the dwarf galaxies remain on the outskirts of this cluster. Next, we analytically model supernova-driven winds and find that main halo progenitors cross-pollute each other more effectively while dwarf galaxy progenitors remain more isolated. Thus, inhomogeneous cross-pollution as a result of different high-z spatial locations of the object progenitors can help to explain observed differences in abundance patterns today. Conversely, these differences are a signature of the inhomogeneity of metal enrichment at early times.


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