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Chemo-dynamical evolution model: Enrichment of r-process elements in the Local Group dwarf galaxies

Published online by Cambridge University Press:  09 May 2016

Yutaka Hirai ,
Yuhri Ishimaru ,
Takayuki R. Saitoh ,
Michiko S. Fujii ,
Jun Hidaka  and
Toshitaka Kajino
Yutaka Hirai
Affiliation:
Department of Astronomy, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan email: [email protected] Division of Theoretical Astronomy, National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo181-8588, Japan Research Fellow of Japan Society for the Promotion of Science
Yuhri Ishimaru
Affiliation:
Department of Natural Sciences, International Christian University, 3-10-2 Osawa, Mitaka, Tokyo 181-8585, Japan Institut d'Astrophysique de Paris, 98bis Boulevard Arago, 75014, Paris, France
Takayuki R. Saitoh
Affiliation:
Earth-Life Science Institute, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8551, Japan
Michiko S. Fujii
Affiliation:
Division of Theoretical Astronomy, National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo181-8588, Japan
Jun Hidaka
Affiliation:
Division of Theoretical Astronomy, National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo181-8588, Japan School of Science and Engineering, Meisei University, 2-1-1 Hodokubo, Hino, Tokyo 191-0042, Japan
Toshitaka Kajino
Affiliation:
Department of Astronomy, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan email: [email protected] Division of Theoretical Astronomy, National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo181-8588, Japan
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Abstract

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Neutron star mergers are one of the candidate astrophysical site(s) of r-process. Several chemical evolution studies however pointed out that the observed abundance of r-process is difficult to reproduce by neutron star mergers. In this study, we aim to clarify the enrichment of r-process elements in the Local Group dwarf galaxies. We carry out numerical simulations of galactic chemo-dynamical evolution using an N-body/smoothed particle hydrodynamics code, ASURA. We construct a chemo-dynamical evolution model for dwarf galaxies assuming that neutron star mergers are the major source of r-process elements. Our models reproduce the observed dispersion in [Eu/Fe] as a function of [Fe/H] with neutron star mergers with a merger time of 100 Myr. We find that star formation efficiency and metal mixing processes during the first ≲ 300 Myr of galaxy evolution are important to reproduce the observations. This study supports that neutron star mergers are a major site of r-process.

Keywords

galaxies: abundances — galaxies: dwarf — galaxies: evolution — Local Group — methods: numerical
Type
Contributed Papers
Information
Proceedings of the International Astronomical Union , Volume 11 , Issue S317: The General Assembly of Galaxy Halos: Structure, Origin and Evolution , August 2015 , pp. 308 - 309
Copyright
Copyright © International Astronomical Union 2016 

References

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