A.S. Font
Phase-space distributions of chemical abundances in Milky Way-type Galaxy halos
Font, A.S.; Johnston, K.V.; Bullock, J.S.; Robertson, B.E.
Authors
K.V. Johnston
J.S. Bullock
B.E. Robertson
Abstract
Motivated by upcoming data from astrometric and spectroscopic surveys of the Galaxy, we explore the chemical abundance properties and phase-space distributions in hierarchically formed stellar halo simulations set in a CDM universe. Our stellar halo metallicities increase with stellar halo mass. The slope of the [Fe/H]-M* trend mimics that of the satellite galaxies that were destroyed to build the halos, implying that the relation propagates hierarchically. All simulated halos contain a significant fraction of old stellar populations accreted more than 10 Gyr ago, and in a few cases some intermediate-age populations exist. In contrast with the Milky Way, many of our simulated stellar halos contain old stellar populations that are metal-rich, originating in the early accretion of massive satellites (M* 109 M). We suggest that the (metal-rich) stellar halo of M31 falls into this category, while the more metal-poor halo of the Milky Way is lacking in early massive accretion events. Interestingly, our hierarchically formed stellar halos often have nonnegligible metallicity gradients in both [Fe/H] and [/Fe]. These gradients extend a few tens of kiloparsecs, and can be as large as 0.5 dex in [Fe/H] and 0.2 dex in [/Fe], with the most metal-poor halo stars typically buried within the central 5 kpc of the galaxy. Finally, we find that chemical abundances can act as a rough substitute for time of accretion of satellite galaxies, and, based on this finding, we propose a criterion for identifying tidal streams spatially by selecting stars with [/Fe] ratios below solar.
Citation
Font, A., Johnston, K., Bullock, J., & Robertson, B. (2006). Phase-space distributions of chemical abundances in Milky Way-type Galaxy halos. Astrophysical Journal, 646(2), 886-898. https://doi.org/10.1086/505131
Journal Article Type | Article |
---|---|
Publication Date | Aug 1, 2006 |
Deposit Date | Apr 23, 2008 |
Journal | Astrophysical Journal |
Print ISSN | 0004-637X |
Electronic ISSN | 1538-4357 |
Publisher | American Astronomical Society |
Peer Reviewed | Peer Reviewed |
Volume | 646 |
Issue | 2 |
Pages | 886-898 |
DOI | https://doi.org/10.1086/505131 |
Keywords | Cosmology, Theory, Galaxies, Abundances, Evolution. |
Publisher URL | http://www.journals.uchicago.edu/ApJ/journal/issues/ApJ/v646n2/64393/brief/64393.abstract.html |
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