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The progenitors of the Milky Way stellar halo: big bricks favoured over little bricks

Deason, A.J.; Belokurov, V.; Weisz, D.R.

The progenitors of the Milky Way stellar halo: big bricks favoured over little bricks Thumbnail


Authors

V. Belokurov

D.R. Weisz



Abstract

We present a census of blue horizontal branch (BHB) and blue straggler (BS) stars belonging to dwarf galaxies and globular clusters, and compare these counts to that of the Milky Way stellar halo. We find, in agreement with earlier studies, that the ratio of BS-to-BHB stars in these satellite populations is dependent on stellar mass. Dwarf galaxies show an increasing BS-to-BHB ratio with luminosity. In contrast, globular clusters display the reverse trend, with NBS/NBHB (≲ 1) decreasing with luminosity. The faintest (L < 105 Lȯ) dwarfs have similar numbers of BS and BHB stars (NBS/NBHB ∼ 1), whereas more-massive dwarfs tend to be dominated by BS stars (NBS/NBHB ∼ 2–40). We find that the BS-to-BHB ratio in the stellar halo is relatively high (NBS/NBHB ∼ 5–6), and thus inconsistent with the low ratios found in both ultra-faint dwarfs and globular clusters. Our results favour more-massive dwarfs as the dominant ‘building blocks’ of the stellar halo, in good agreement with current predictions from Λ cold dark matter models.

Citation

Deason, A., Belokurov, V., & Weisz, D. (2015). The progenitors of the Milky Way stellar halo: big bricks favoured over little bricks. Monthly Notices of the Royal Astronomical Society: Letters, 448(1), L77-L81. https://doi.org/10.1093/mnrasl/slv001

Journal Article Type Article
Acceptance Date Jan 3, 2015
Online Publication Date Feb 2, 2015
Publication Date Mar 21, 2015
Deposit Date Feb 20, 2017
Publicly Available Date Mar 27, 2017
Journal Monthly Notices of the Royal Astronomical Society: Letters
Electronic ISSN 1745-3933
Publisher Oxford University Press
Peer Reviewed Peer Reviewed
Volume 448
Issue 1
Pages L77-L81
DOI https://doi.org/10.1093/mnrasl/slv001
Related Public URLs https://arxiv.org/abs/1501.02806

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Copyright Statement
This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society Letters ©: 2015 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.







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