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Evidence from APOGEE for the presence of a major building block of the halo buried in the inner Galaxy

Horta, D, Schiavon, RP, Mackereth, JT, Pfeffer, J, Mason, AC, Kisku, S, Fragkoudi, F, Prieto, CA, Cunha, K, Hasselquist, S, Holtzman, J, Majewski, SR, Nataf, D, O'Connell, RW, Schultheis, M and Smith, VV (2020) Evidence from APOGEE for the presence of a major building block of the halo buried in the inner Galaxy. Monthly Notices of the Royal Astronomical Society, 500 (1). pp. 1385-1403. ISSN 0035-8711

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Abstract

We report evidence from APOGEE for the presence of a new metal-poor stellar structure located within ∼4 kpc of the Galactic Centre. Characterized by a chemical composition resembling those of low-mass satellites of the Milky Way, this new inner Galaxy structure (IGS) seems to be chemically and dynamically detached from more metal-rich populations in the inner Galaxy. We conjecture that this structure is associated with an accretion event that likely occurred in the early life of the Milky Way. Comparing the mean elemental abundances of this structure with predictions from cosmological numerical simulations, we estimate that the progenitor system had a stellar mass of ∼5 × 108 M⊙, or approximately twice the mass of the recently discovered Gaia-Enceladus/Sausage system. We find that the accreted:in situ ratio within our metal-poor ([Fe/H] < –0.8) bulge sample is somewhere between 1:3 and 1:2, confirming predictions of cosmological numerical simulations by various groups.

Item Type: Article
Additional Information: This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society: 2020 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved
Uncontrolled Keywords: ABUNDANCES; Astronomy & Astrophysics; CLUSTERS; EVOLUTION; GALACTIC BULGE; Galaxy: abundances; Galaxy: evolution; Galaxy: formation; Galaxy: halo; Galaxy: kinematics and dynamics; Galaxy: structure; GIANTS; MILKY; ORIGIN; Physical Sciences; POPULATIONS; Science & Technology; STARS; WAY STELLAR HALO; Science & Technology; Physical Sciences; Astronomy & Astrophysics; Galaxy: abundances; Galaxy: evolution; Galaxy: formation; Galaxy: halo; Galaxy: kinematics and dynamics; Galaxy: structure; WAY STELLAR HALO; GALACTIC BULGE; MILKY; STARS; POPULATIONS; ABUNDANCES; EVOLUTION; CLUSTERS; GIANTS; ORIGIN; astro-ph.GA; astro-ph.GA; Astronomy & Astrophysics; 0201 Astronomical and Space Sciences
Subjects: Q Science > QB Astronomy
Divisions: Astrophysics Research Institute
Publisher: Royal Astronomical Society
SWORD Depositor: A Symplectic
Date Deposited: 12 Oct 2022 09:31
Last Modified: 12 Oct 2022 09:31
DOI or ID number: 10.1093/mnras/staa2987
URI: https://researchonline.ljmu.ac.uk/id/eprint/17820
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