Skip to main content

Research Repository

Advanced Search

Chemical abundance distributions of galactic halos and their satellite systems in a Lambda CDM Universe

Font, AS; Johnston, KV; Bullock, JS; Robertson, BE

Authors

AS Font

KV Johnston

JS Bullock

BE Robertson



Abstract

We present a cosmologically motivated model for the hierarchical formation of the stellar halo that includes a semianalytic treatment of galactic chemical enrichment coupled to numerical simulations that track the orbital evolution and tidal disruption of satellites. A major motivating factor in this investigation is the observed systematic difference between the chemical abundances of stars in satellite galaxies and those in the Milky Way halo. Specifically, for the same [Fe/H] values, stars in neighboring satellite galaxies display significantly lower [alpha/Fe] ratios than stars in the halo. We find that the observed chemical abundance patterns are a natural outcome of the process of hierarchical assembly of the Galaxy. This result follows because the stellar halo in this context is built up from satellite galaxies accreted early on (more than 8-9 Gyr ago) and enriched in alpha-elements produced in Type II supernovae. In contrast, satellites that still survive today are typically accreted late (within the last 4-5 Gyr) with nearly solar [alpha/Fe] values as a result of contributions from both Type II and Type Ia supernovae. We use our model to investigate the abundance distribution functions (using both [Fe/H] and [alpha/Fe] ratios) for stars in the halo and in surviving satellites. Our results suggest that the shapes and peaks in the abundance distribution functions provide a direct probe of the accretion histories of galaxies.

Citation

Font, A., Johnston, K., Bullock, J., & Robertson, B. (2006). Chemical abundance distributions of galactic halos and their satellite systems in a Lambda CDM Universe. Astrophysical Journal, 638(2), 585-595. https://doi.org/10.1086/498970

Journal Article Type Article
Publication Date Feb 1, 2006
Deposit Date Jan 10, 2008
Journal Astrophysical Journal
Print ISSN 0004-637X
Electronic ISSN 1538-4357
Publisher American Astronomical Society
Peer Reviewed Peer Reviewed
Volume 638
Issue 2
Pages 585-595
DOI https://doi.org/10.1086/498970
Keywords Cosmology, Theory, Galaxies, Abundances, Evolution.

Downloadable Citations