Unified Analysis of Structure Formations and Evolutions in the Deep Universe
Grant-in-Aid for Scientific Research (C).
|Research Institution||National Astronomical Observatory of Japan|
GOUDA Naoteru National Astronomical Observatory of Japan, Astrometry and Celestial Mechanics, Professor, 位置天文・天体力学研究系, 教授 (50202073)
|Project Fiscal Year
1998 – 2000
Completed(Fiscal Year 2000)
|Budget Amount *help
¥2,300,000 (Direct Cost : ¥2,300,000)
Fiscal Year 2000 : ¥700,000 (Direct Cost : ¥700,000)
Fiscal Year 1999 : ¥600,000 (Direct Cost : ¥600,000)
Fiscal Year 1998 : ¥1,000,000 (Direct Cost : ¥1,000,000)
|Keywords||galaxy formations / large scale structues in the universe / self-gravitating many-body systems / 銀河形成 / 宇宙の大構造 / 自己重力多体系|
1. We developed a semi-analytic model for resolving the problems of galaxy formations and got some interesting results using this semi-analytic model based on the hierarchical clustering. By using this model, we tried to clarify what physical processes, which have never been taken into account in the galaxy formation models, influence on galaxy formations and evolutions. Furthermore, we tried to constrain the cosmological models and some physical processes concerned in the galaxy formations, such as star formations. The detailed topics on the galaxy formations are shown below.
(1) The effects of merging histories of proto-objects on the angular momentum distributions of the present-time dark matter haloes were clarified.
(2) We investigated the effects of the UV background radiation on galaxy formations by using the semi-analytic model including the photoionization process and we clarified its effects on the galaxy formations.
(3) We calculated the detection rate of cold gas in ellipti
cal galaxies using the semi-analytic model of galaxy formation, and compared it with observations. Then we could constrain the star formation rates in the galaxy formations.
(4) We clarified the physical origin of the color-magnitude relation of elliptical galaxies in clusters of galaxies in the hierarchical clustering scenario by using the semi-analytic model.
(5) The galaxy number counts are analyzed by using the semi-analytic model based on the hierarchical clustering scenario. In this model, we introduced the selection effects due to the rapidly dimming surface brightness at high redshift and the absorption by intergalactic HI clouds and by internal dust, which are not considered in the previous analysis of galaxy counts.
2. The relation between relaxation, the time scale of Lyapunov instabilities, and the Kolmogorov-Sinai time in a one-dimensional gravitating sheet is studied. We found that the relaxation time to the final thermal equilibrium differs from the inverse of the Lyapunov exponents and the Kolmogorov-Sinai time.
3. We found the relation between the two-point spatial correlation function and the density profile of the dark matter halos in the strongly nonlinear regime.
Research Output (18results)