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The Dual Origin of Stellar Halos. II. Chemical Abundances as Tracers of Formation History

Zolotov, Adi and Willman, Beth and Brooks, Alyson M. and Governato, Fabio and Hogg, David W. and Shen, Sijing and Wadsley, James (2010) The Dual Origin of Stellar Halos. II. Chemical Abundances as Tracers of Formation History. Astrophysical Journal, 721 (1). pp. 738-743. ISSN 0004-637X.

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Fully cosmological, high-resolution N-body+smooth particle hydrodynamic simulations are used to investigate the chemical abundance trends of stars in simulated stellar halos as a function of their origin. These simulations employ a physically motivated supernova feedback recipe, as well as metal enrichment, metal cooling, and metal diffusion. As presented in an earlier paper, the simulated galaxies in this study are surrounded by stellar halos whose inner regions contain both stars accreted from satellite galaxies and stars formed in situ in the central regions of the main galaxies and later displaced by mergers into their inner halos. The abundance patterns ([Fe/H] and [O/Fe]) of halo stars located within 10 kpc of a solar-like observer are analyzed. We find that for galaxies which have not experienced a recent major merger, in situ stars at the high [Fe/H] end of the metallicity distribution function are more [α/Fe]-rich than accreted stars at similar [Fe/H]. This dichotomy in the [O/Fe] of halo stars at a given [Fe/H] results from the different potential wells within which in situ and accreted halo stars form. These results qualitatively match recent observations of local Milky Way halo stars. It may thus be possible for observers to uncover the relative contribution of different physical processes to the formation of stellar halos by observing such trends in the halo populations of the Milky Way and other local L^* galaxies.

Item Type:Article
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URLURL TypeDescription
Willman, Beth0000-0003-2892-9906
Hogg, David W.0000-0003-2866-9403
Additional Information:© 2010 American Astronomical Society. Received 2010 April 21; accepted 2010 August 2; published 2010 September 1. We thank the anonymous referee for helping to greatly improve the paper. We thank Chris Brook for helpful conversations and Joe Cammisa at Haverford for computing support. A.Z. and B.W. acknowledge support from the NSF grant AST-0908446. All simulations were run using the NASA Advanced Supercomputer Pleiades. F.G. acknowledges support from the HST GO-1125, NSF AST-0607819, and NASA ATP NNX08AG84G grants. A.M.B. acknowledges support from the Sherman Fairchild Foundation.
Funding AgencyGrant Number
Sherman Fairchild FoundationUNSPECIFIED
Subject Keywords:Galaxy: abundances; Galaxy: formation; Galaxy: halo; methods: numerical
Issue or Number:1
Classification Code:PACS: 98.35.Ac; 98.35.Ln; 98.35.Gi; 98.35.Hj
Record Number:CaltechAUTHORS:20101026-100909346
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Official Citation:Adi Zolotov et al 2010 ApJ 721 738 doi: 10.1088/0004-637X/721/1/738
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:20533
Deposited By: Jason Perez
Deposited On:26 Oct 2010 18:34
Last Modified:09 Mar 2020 13:18

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