Thin disc, thick disc and halo in a simulated galaxy
Entity
UAM. Departamento de Física TeóricaPublisher
Oxford University Press; Royal Astronomical SocietyDate
2012-10-11Citation
10.1111/j.1365-2966.2012.21738.x
Monthly Notices of the Royal Astronomical Society 426.1 (2012): 690-700
ISSN
0035-8711 (print); 1365-2966 (online)DOI
10.1111/j.1365-2966.2012.21738.xFunded by
BKG and CBB acknowledge the support of the UK’s Science & Technology Facilities Council (ST/F002432/1 & ST/H00260X/1). BKG and KP acknowledge the generous visitor support provided by Saint Mary’s University and Monash University. TRQ was supported by NSF Grant AST- 0908499. We thank the DEISA consortium, co-funded through EU FP6 project RI-031513 and the FP7 project RI-222919, for support within the DEISA Extreme Computing Initiative, the UK’s National Cosmology Supercomputer (COSMOS) and the University of Central Lancashire’s High Performance Computing Facility. CBB and AVM acknowledge funding by Sonderforschungsbereich SFB 881 ‘The Milky Way System’(sub-project A1) of the German Research Foundation (DFG)Project
info:eu-repo/grantAgreement/EC/EP7/222919Editor's Version
http://dx.doi.org/10.1111/j.1365-2966.2012.21738.xSubjects
Galaxy:disc; Galaxy: evolution; Galaxy: formation; Galaxies: evolution; Galaxies: formation; FísicaNote
This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society ©2012 RAS © 2012 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.Rights
© 2012 RAS; © 2012 The AuthorsAbstract
Within a cosmological hydrodynamical simulation, we form a disc galaxy with sub-components which can be assigned to a thin stellar disc, thick disc and a low-mass stellar halo via a chemical decomposition. The thin- and thick-disc populations so selected are distinct in their ages, kinematics and metallicities. Thin-disc stars are young (<6.6 Gyr), possess low velocity dispersion (σ U, V, W = 41, 31, 25 kms -1), high [Fe/H] and low [O/Fe]. Conversely, the thick-disc stars are old (6.6 < age < 9.8Gyr), lag the thin disc by ∼21 kms -1, possess higher velocity dispersion (σ U, V, W = 49, 44, 35 kms -1) and have relatively low [Fe/H] and high [O/Fe]. The halo component comprises less than 4 per cent of stars in the 'solar annulus' of the simulation, has low metallicity, a velocity ellipsoid defined by σ U, V, W = 62, 46, 45 kms -1 and is formed primarily in situ during an early merger epoch. Gas-rich mergers during this epoch play a major role in fuelling the formation of the old-disc stars (the thick disc). We demonstrate that this is consistent with studies which show that cold accretion is the main source of a disc galaxy's baryons. Our simulation initially forms a relatively short (scalelength ∼1.7kpc at z = 1) and kinematically hot disc, primarily from gas accreted during the galaxy's merger epoch. Far from being a competing formation scenario, we show that migration is crucial for reconciling the short, hot, discs which form at high redshift in Λ cold dark matter, with the properties of the thick disc at z = 0. The thick disc, as defined by its abundances, maintains its relatively short scalelength at z = 0 (2.31kpc) compared with the total disc scalelength of 2.73kpc. The inside-out nature of disc growth is imprinted in the evolution of abundances such that the metal-poor α-young population has a larger scalelength (4.07kpc) than the more chemically evolved metal-rich α-young population (2.74kpc)
Files in this item
Google Scholar:Brook, C. B.
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Stinson, G. S.
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Gibson, B. K.
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Kawata, D.
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House, E. L.
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Miranda, M. S.
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Pilkington, K.
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Roškar, R.
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Wadsley, J.
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Quinn, T. R.
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Macciò, A. V.
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