| Co-Investigator(Kenkyū-buntansha) |
EBISUZAKI Toshikazu The Institute of Physical and Chemical Research Senior Researcher, 計算科学, 主任研究員 (10183021)
TAIJI Makoto The University of Tokyo, Graduate School of Arts and Sciences, Assistant, 大学院・総合文化研究科, 助手 (10242025)
MAKINO Junichiro The University of Tokyo, Graduate School of Arts and Sciences, Associate Profess, 大学院・総合文化研究科, 助教授 (50229340)
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| Research Abstract |
In this year, we continued the simulation of the evolution of globular clusters, galaxies and clusters of galaxies using GRAPE-4. In addition, we developed a new host interface board for GRAPE-4, which allows use to use faster host computers. For this new host interface board we adopted the PCI bus, which is now available on wide variety of computers from personal computers to supercomputers. We bought high-performance workstations with this PCI interface as new host computers, fast and large tape systems to save the data, and enhanced the memory capacity of host computers
Main scientific results of this year include (a) The determination of the structure of the central region of the CDM halo, (b) The study of the evolution of the massive black hole binaries in merging galaxies, and (c) the systematic survey of the effect of encounters to the structure of galaxies in the clusters.
Here we briefly summarize (a). Previous simulations of the formation of the dark matter halo in galactic scale typically employed only 20,000-30,000 particles. Because of this small number of particles, the structure within 10 kilo parsec was strongly affected by the two-body relaxation effect, which is not present in real galaxies. We performed the simulation using 786,432 particles, and successfully determined the structure down to 1 kilo parsec. The result is that the inner region is almost isothermal with temperature slightly decreasing inward, which is inconsistent with the observed structure of large elliptical galaxies. This result and the simulation of galaxy merger with central black holes strongly suggest the dynamical effect of massive central objects is crucial to explain the observed structure of large ellipticals.
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