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Enrichment of Heavy Elements in Chemo-Dynamical Simulations of Dwarf Galaxies

Published online by Cambridge University Press:  30 October 2019

Yutaka Hirai Open the ORCID record for Yutaka Hirai [Opens in a new window] ,
Takayuki R. Saitoh ,
Shinya Wanajo  and
Michiko S. Fujii
Yutaka Hirai
Affiliation:
RIKEN Center for Computational Science, 7-1-26 Minatojima-minami-machi, Chuo-ku, Kobe, Hyogo 650-0047, Japan email: [email protected]
Takayuki R. Saitoh
Affiliation:
Earth-Life Science Institute, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8551, Japan
Shinya Wanajo
Affiliation:
Department of Engineering and Applied Sciences, Faculty of Science and Technology, Sophia University, 7-1 Kioicho, Chiyoda-ku, Tokyo 102-8554, Japan RIKEN iTHEMS Research Group, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
Michiko S. Fujii
Affiliation:
Department of Astronomy, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
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Abstract

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Abundances of heavy elements in dwarf galaxies reflect their early evolutionary histories. Recent astronomical observations have shown that there are star-to-star scatters in the abundances of r-process elements and the decreasing trend of Zn toward higher metallicity in extremely metal-poor stars. However, the enrichment of heavy elements is not well understood. Here we performed a series of high-resolution N-body/smoothed particle hydrodynamics simulations of dwarf galaxies. We find that neutron star mergers can explain ratios of r-process elements to iron in dwarf galaxies due to their suppressed star formation rates. We also find that stars with [Zn/Fe] ≳ 0.5 reflect the ejecta from electron-capture supernovae. Inhomogeneity of the metals in the interstellar medium causes the scatters of heavy elements. We estimate that the timescale of metal mixing is ≲ 40 Myr using heavy element abundances in metal-poor stars.

Keywords

diffusiongalaxies: abundancesgalaxies: dwarfgalaxies: evolutionhydrodynamicsISM: abundancesmethods: numericalnucleosynthesisstars: abundancesLocal Group
Type
Contributed Papers
Information
Proceedings of the International Astronomical Union , Volume 14 , Symposium S344: Dwarf Galaxies: From the Deep Universe to the Present , August 2018 , pp. 197 - 200
Copyright
© International Astronomical Union 2019 

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