Chemical Abundance Patterns and the Early Environment of Dwarf Galaxies

TL;DR

This study investigates how early environmental factors and inhomogeneous metal enrichment influenced the chemical abundance patterns observed in dwarf galaxies and the Milky Way halo, using simulations and analytical models.

Contribution

It introduces a model linking early spatial distribution of progenitors to observed abundance differences, highlighting the role of inhomogeneous cross-pollution.

Findings

Progenitor halos of the main halo cluster at high redshift, while satellites remain isolated.

Main halo progenitors experience more effective cross-pollution.

Differences in abundance patterns reflect early inhomogeneous metal enrichment.

Abstract

Recent observations suggest that abundance pattern differences exist between low metallicity stars in the Milky Way stellar halo and those in the dwarf satellite galaxies. This paper takes 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 satellites 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 satellite galaxies remain on the outskirts of this cluster. Next, analytically modeled supernova-driven winds show that main halo progenitors cross-pollute each other more effectively while satellite galaxy progenitors remain more isolated. Thus, inhomogeneous cross-pollution as a result of different high-z spatial locations of each system's 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.