THE DUAL ORIGIN OF STELLAR HALOS. II. CHEMICAL ABUNDANCES AS TRACERS OF FORMATION HISTORY

Journal Article · Mon Sep 20 04:00:00 EDT 2010 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/721/1/738· OSTI ID:21464812

Zolotov, Adi; Hogg, David W ^[1]; Willman, Beth ^[2]; Brooks, Alyson M ^[3]; Governato, Fabio ^[4]; Shen, Sijing; Wadsley, James ^[5]

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1. Center for Cosmology and Particle Physics, Department of Physics, New York University, 4 Washington Place, New York, NY 10003 (United States)
2. Haverford College, Department of Astronomy, 370 Lancaster Avenue, Haverford, PA 19041 (United States)
3. California Institute of Technology, M/C 350-17, Pasadena, CA 91125 (United States)
4. Department of Astronomy, University of Washington, P.O. Box 351580, Seattle, WA 98195 (United States)
5. Department of Physics and Astronomy, McMaster University, Hamilton, Ontario L88 4M1 (Canada)

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 [{alpha}/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{sup *} galaxies.

• OSTI ID: 21464812
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 1 Vol. 721; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ABUNDANCE
DISTRIBUTION FUNCTIONS
EVOLUTION
FUNCTIONS
GALACTIC EVOLUTION
GALAXIES
MILKY WAY
SATELLITES
SIMULATION
STARS