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Geometrical structures of chemically decomposed thick and thin disk populations

Kawata, Daisuke; Brook, Chris; Rahimi, Awat; Gibson, Brad

Authors

Chris Brook

Daisuke Kawata

Awat Rahimi

Abstract

We summarize the thick and thin disk formation commonly seen in cosmological N-body simulations. As suggested in Brook et al. (2004), a hierarchical clustering scenario causes multiple minor gas-rich mergers, and leads to the formation of a kinematically hot disk, thick disk population, at a high redshift. Once the mergers become less significant at a later epoch, the thin disk population starts building up. Because in this scenario the thick disk population forms intensively at high redshift through multiple gas-rich mergers, the thick disk population is compact and has systematically higher [α/Fe] abundance than the thin disk population. We discuss that the thick disk population would be affected by the formation of the thin disk and suffer from the radial migration, which helps the thick disk population to be observed in the solar neighborhood. In addition, we show that the current cosmological simulations also naturally predict that the thin disk population is flaring at the outer region. As shown in Rahimi et al. (2014), at high vertical height from the disk plane, the compact thick disk population (low metallicity and high [α/Fe]) is dominant in the inner region and the flaring thin disk population (high metallicity and low [α/Fe]) contributes more in the outer region. This helps to explain the positive radial metallicity gradient and negative radial [α/Fe] gradient observed at high vertical height in the Milky Way stellar disk.

Book Type Book Chapter
Publication Date 2017
Journal Multi-object spectroscopy in the next decade
Peer Reviewed Not Peer Reviewed
Pages 27
Series Title ASP Conference Series
Series Number 507
Series ISSN 1050-3390
ISBN 9781583818985
Keywords Thick and thin disk formation; Redshift
Publisher URL Published chapter available at http://www.aspbooks.org...etails/?paper_id=37842.
Copyright Statement ©2017 University of Hull

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