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Title: The Eating Habits of Milky Way Mass Halos: Destroyed Dwarf Satellites and the Metallicity Distribution of Accreted Stars

In this paper, we study the mass spectrum of destroyed dwarfs that contribute to the accreted stellar mass of Milky Way (MW)-mass (M vir ~ 10 12.1 M ) halos using a suite of 45 zoom-in dissipationless simulations. Empirical models are employed to relate (peak) subhalo mass to dwarf stellar mass, and we use constraints from z = 0 observations and hydrodynamical simulations to estimate the metallicity distribution of the accreted stellar material. The dominant contributors to the accreted stellar mass are relatively massive dwarfs with M star ~ 10 8–10 10M . Halos with more quiescent accretion histories tend to have lower mass progenitors (10 8–10 9 M ), and lower overall accreted stellar masses. Ultra-faint mass (M star < 10 5 M ) dwarfs contribute a negligible amount (<<1%) to the accreted stellar mass and, despite having low average metallicities, supply a small fraction (~2%–5%) of the very metal-poor stars with [Fe/H] < -2. Dwarfs with masses 10 5 < M star/M < 10 8 provide a substantial amount of the very metal-poor stellar material (~40%–80%), and even relatively metal-rich dwarfs with M star > 10 8 M can contribute a considerable fraction (~20%–60%) of metal-poormore » stars if their metallicity distributions have significant metal-poor tails. Finally, we find that the generic assumption of a quiescent assembly history for the MW halo seems to be in tension with the mass spectrum of its surviving dwarfs. In conclusion, we suggest that the MW could be a "transient fossil"; a quiescent halo with a recent accretion event(s) that disguises the preceding formation history of the halo.« less
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  1. Stanford Univ., CA (United States). Kavli Inst. for Particle Astrophysics and Cosmology and Physics Dept.; SLAC National Accelerator Lab., Menlo Park, CA (United States)
Publication Date:
Report Number(s):
Journal ID: ISSN 1538-4357; arXiv:1601.07905
Grant/Contract Number:
AC02-76SF00515; AC02-05CH11231
Accepted Manuscript
Journal Name:
The Astrophysical Journal (Online)
Additional Journal Information:
Journal Name: The Astrophysical Journal (Online); Journal Volume: 821; Journal Issue: 1; Journal ID: ISSN 1538-4357
Institute of Physics (IOP)
Research Org:
SLAC National Accelerator Lab., Menlo Park, CA (United States)
Sponsoring Org:
USDOE Office of Science (SC)
Country of Publication:
United States
79 ASTRONOMY AND ASTROPHYSICS; galaxy formation; halo; stellar content; dwarf; interactions; Local Group
OSTI Identifier: