| Project/Area Number |
13440058
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Astronomy
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| Research Institution | The University of Tokyo |
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Principal Investigator |
MAKINO Junichiro The University of Tokyo, Graduate School of Science, Associate Professor, 大学院・理学系研究科, 助教授 (50229340)
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| Co-Investigator(Kenkyū-buntansha) |
FUKUSHIGE Toshiyuki Graduate School of Arts and Sciences, Assistant Professor, 大学院・総合文化研究科, 助手 (60282513)
NOMOTO Ken'ichi Graduate School of Science, Professor, 大学院・理学系研究科, 教授 (90110676)
SUDO Yasushi Graduate School of Science, Associate Professor, 大学院・理学系研究科, 助教授 (20206569)
KOKUBO Eiichiro National Astronamical Observatory of Japan Theore Tical Astrophysics Division, Assistant Professor, 理論天文学研究系, 助手 (90332163)
HABE Asao Hokkaido University, Graduate School of Science, Associate Professor, 大学院・理学研究科, 助教授 (90180926)
穂積 俊輔 滋賀大学, 教育学部, 助教授 (90229203)
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| Project Period (FY) |
2001 – 2002
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| Project Status |
Completed (Fiscal Year 2002)
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| Budget Amount *help |
¥17,000,000 (Direct Cost: ¥17,000,000)
Fiscal Year 2002: ¥4,100,000 (Direct Cost: ¥4,100,000)
Fiscal Year 2001: ¥12,900,000 (Direct Cost: ¥12,900,000)
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| Keywords | large scale stuctuve / galaxy formation / dark matter halo / cosmology / N-body simulation / dwarf galaxy / cold dark matter / 宇宙の大規模構造 / ダークハロー / 並列計算機 / 専用計算機 / ツリー法 / 衛星銀河 / 銀河団 |
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| Research Abstract |
1. We have developed a high-efficiency parallel implementation of the Barnes-Hut tree algorithm on parallel GRAPE system. Using this calculation code, it is now feasible to perform simulations of cosmological structure formation in the spatial scale smaller than clusters of galaxies using 〜 10^8 particles. Only one such simulation has been previously reported.
2. By cosmological simulations with more than 30 million particles, we have determined the slope of the central cusp of the dark-matter halo in CDM cosmology with unprecedented accuracy and reliability. The slope is around -1.4. We have not observed any tendency of the slope to approach to ―1. This slope does not depend on the cosmological models.
3. We have found the reason of the discrepancy between N-body simulations and semi-analytic calculations of the orbital evolution of satellite galaxies. The evolution of the satellite galaxies in recent high-accuracy N-body simulations turned out to be significantly slower than the result of approximate calculations using Chandrasekhar's dynamical friction formula. We found that the discrepancy is not due to the dynamical friction formula itself, but due to the common exercise of taking the size of the parent galaxy as the upper limit for the Coulomb logarithm. By taking the theoretical preferred value, namely the distance of the satellite from the center of the parent galaxy, we resolved the discrepancy. In the case of the satellite from internal degree of freedom, we found that the evolution is faster than that for analytic dynamical friction formula.
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