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Chemodynamical Simulations of the Milky Way Galaxy - Inhomogeneous Chemical Enrichment

Published online by Cambridge University Press:  06 January 2014

Chiaki Kobayashi
Chiaki Kobayashi*
Affiliation:
Centre for Astrophysics Research, School of Physics, Astronomy and Mathematics, University of Hertfordshire; College Lane, Hatfield AL10 9AB, UK email: [email protected]
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Abstract

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The predictions of our chemodynamical simulations from cosmological initial conditions are as follows: The disk formed Inside-out. Metallicity radial and vertical gradients exist, but no [α/Fe] radial gradient. Metallicity radial gradient is steeper at higher redshifts. The [α/Fe]-[Fe/H] relation is caused by the delayed enrichment of Type Ia supernovae (not with long lifetimes, but with the metallicity effect). The bulge formed through the assembly of small gas-rich galaxies at high redshifts. [α/Fe] is higher, [Mn/Fe] is lower, [(Na, Al)/Fe] are higher than the disk. Metallicity and [α/Fe] vertical gradients exist, which is caused by the increase of metal-rich and low [α/Fe] populations at lower latitudes. Bars may form later, which may show boxy and cylindrical rotation. Half of thick disk stars (kinetically selected) come from minor mergers. [α/Fe] is higher, and [Mn/Fe] is lower than the thin disk, but [(Na, Al, Cu, Zn)/Fe] are lower than the bulge. There are metallicity vertical, weak metallicity radial, and no [α/Fe] radial gradients. It would be interesting to compare the predictions with other models such as radial mixing, disk heating, and clumpy disks.

For the solar neighborhood, the frequency distributions of elements from oxygen to zinc are in excellent agreement not only for the average values but also for the scatter. In chemodynamical simulations, chemical enrichment takes place inhomogeneously, and the scatter originates from a combination of various effects - mergers, migration, and in-situ. The inhomogeneous enrichment is important in reproducing observed nitrogen abundances, and also in understanding elemental abundance patterns of dwarf spheroidal galaxies and carbon-enhanced damped Lyman α systems.

Keywords

Galaxy: abundances — Galaxy: evolution — Galaxy: formation — methods: numerical — stars: supernovae
Type
Contributed Papers
Information
Proceedings of the International Astronomical Union , Volume 9 , Symposium S298: Setting the scene for Gaia and LAMOST , May 2013 , pp. 167 - 178
Copyright
Copyright © International Astronomical Union 2014 

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