Tracing galaxy formation with stellar halos. II. relating substructure in phase and abundance space to accretion histories

Kathryn V. Johnston, James S. Bullock, Sanjib Sharma, Andreea Font, Brant E Robertson, Samuel N. Leitner

Research output: Contribution to journalArticle

205 Citations (Scopus)

Abstract

This paper explores the mapping between the observable properties of a stellar halo in phase and abundance space and the parent galaxy's accretion history in terms of the characteristic epoch of accretion and mass and orbits of progenitor objects. The study utilizes a suite of 11 stellar halo models constructed within the context of a standard ACDM cosmology. The results demonstrate that coordinate-space studies are sensitive to the recent (0-8 Gyr ago) merger histories of galaxies (this timescale corresponds to the last few percent to tens of percent of mass accretion for a Milky Way-type galaxy). Specifically, the frequency, sky coverage, and fraction of stars in substructures in the stellar halo as a function of surface brightness are indicators of the importance of recent merging and of the luminosity function of in-falling dwarfs. The morphology of features serves as a guide to the orbital distribution of those dwarfs. Constraints on the earlier merger history (>8 Gyr ago) can be gleaned from the abundance patterns in halo stars: within our models, dramatic differences in the dominant epoch of accretion or luminosity function of progenitor objects leave clear signatures in the [α/Fe] and [Fe/H] distributions of the stellar halo; halos dominated by very early accretion have higher average [α/Fe], while those dominated by high-luminosity satellites have higher [Fe/H]. This insight can be applied to reconstruct much about the merger histories of nearby galaxies from current and future data sets.

Original languageEnglish (US)
Pages (from-to)936-957
Number of pages22
JournalAstrophysical Journal
Volume689
Issue number2
DOIs
StatePublished - Dec 20 2008
Externally publishedYes

Fingerprint

galactic evolution
tracing
substructures
halos
accretion
histories
merger
history
galaxies
luminosity
time measurement
stars
cosmology
falling
sky
brightness
timescale
signatures
orbits
orbitals

Keywords

  • Dark matter
  • Galaxies: dwarf
  • Galaxies: evolution
  • Galaxies: formation
  • Galaxies: halos
  • Galaxies: kinematics and dynamics
  • Galaxy: evolution
  • Galaxy: formation
  • Galaxy: halo
  • Galaxy: kinematics and dynamics
  • Local Group

ASJC Scopus subject areas

  • Space and Planetary Science
  • Astronomy and Astrophysics

Cite this

Tracing galaxy formation with stellar halos. II. relating substructure in phase and abundance space to accretion histories. / Johnston, Kathryn V.; Bullock, James S.; Sharma, Sanjib; Font, Andreea; Robertson, Brant E; Leitner, Samuel N.

In: Astrophysical Journal, Vol. 689, No. 2, 20.12.2008, p. 936-957.

Research output: Contribution to journalArticle

Johnston, Kathryn V. ; Bullock, James S. ; Sharma, Sanjib ; Font, Andreea ; Robertson, Brant E ; Leitner, Samuel N. / Tracing galaxy formation with stellar halos. II. relating substructure in phase and abundance space to accretion histories. In: Astrophysical Journal. 2008 ; Vol. 689, No. 2. pp. 936-957.
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