2004 Fiscal Year Final Research Report Summary
Formation and Evolution of the Milky Way
| Project/Area Number |
15540241
|
|---|
| Research Category |
Grant-in-Aid for Scientific Research (C)
|
| Allocation Type | Single-year Grants |
|---|
| Section | 一般 |
|---|
| Research Field |
Astronomy
|
|---|
| Research Institution | Tohoku University |
|---|
Principal Investigator |
CHIBA Masashi Tohoku University, Graduate School of Science, Professor, 大学院・理学研究科, 教授 (50217246)
|
|---|
| Co-Investigator(Kenkyū-buntansha) |
TOSA Makoto Tohoku University, Graduate School of Science, Professor, 大学院・理学研究科, 教授 (50022728)
AOKI Wako National Astronomical Observatory of Japan, Division of Optical and Infrared Astronomy, Assistant Professor, 光赤外研究部, 主任研究員 (20321581)
KODAMA Tadayuki National Astronomical Observatory of Japan, Division of Optical and Infrared Astronomy, Associate Professor, 光赤外研究部, 助教授 (80343101)
|
|---|
| Project Period (FY) |
2003 – 2004
|
| Keywords | Galaxy |
|---|
| Research Abstract |
Structural, kinematical, and chemical properties of old, metal-poor stellar haloes of galaxies have long provided valuable information on early formation histories of galaxies, in particular; galaxies in the Local Group. For example, the observed correlation between chemical and dynamical properties of Galactic halo stars or lack thereof have enabled authors to discuss whether the Galaxy was formed by a monolithic collapse within a few dynamical timescales. Numerical simulations of Galaxy formation based on the cold dark matter model have demonstrated that basic physical processes involved in the formation of the metal-poor, old stellar halo in a disk galaxy are described by both dissipative and dissipationless merging of subgalactic clumps and their resultant tidal disruption in the course of gravitational contraction of the galaxy at high redshift : Thus, understanding of star formation and chemical evolution histories in subgalactic clumps (i.e., progenitors of low-mass dwarfs) are
… More
key for better understanding of the origin of galactic stellar halos.
Also, although many observational and theoretical studies in the young universe have already provided important constraints on the cosmic reionization history, it remains yet to be explored in the present-day universe as to (1)whether old stellar halos of galaxies contain the fossil records of reionization history and (2)what observations of stellar halos can provide what clues to the possible influences of reionization on galaxy formation processes. Physical properties of metal-poor, old stellar halos in galaxies beyond the Local Group have been recently investigated by the Hubble Space Telescope and large ground--based telescopes. Furthermore, recent numerical studies provided some specific predictions on star formation histories of dwarf galaxies under the influence of reionization. Thus it is quite timely to discuss the above questions based on the comparison between observations and numerical simulations addressing the possible influence of reionization on the properties of galactic stellar halos.
Taking advantage of this grant awarded, we have made a lot of progresses about the above issue as well as other relevant issues on the formation and evolution of the Milky Way and Local Group galaxies. Furthermore, we have studied the structure of dark matter surrounding the visible parts of galaxies, which is supposed to play an important role in the formation process of galaxies through hierarchical clustering. For this purpose, we have focused on gravitational lensing phenomena on background sources (such as QSOs), to set limits on mass substructure in lensing galaxies. Both observational and theoretical analyses have been made on this issue. Less
|
-
-
-
-
-
[Journal Article] The Surprisingly Steep Mass Profile of A1689, from a Lensing Analysis of Subaru Images2005
Author(s)
Broadhurst, T., Takada, M., Umetsu, K., Kong, X., Arimoto, N., Chiba, M., Futamase, T.
-
Journal Title
Description
「研究成果報告書概要(欧文)」より
-
-
-
-
-
-
[Journal Article] Explaining the Mysterious Age Gap of Globular Clusters in the Large Magellanic Cloud2004
Author(s)
Bekki, K., Couch, W.J., Beasley, M.A., Forbes, D.A., Chiba, M., Da Costa, G.S.
-
Journal Title
Description
「研究成果報告書概要(欧文)」より
-
