1998 Fiscal Year Final Research Report Summary
Structure and Evolution of Clusters of Galaxies by X-Ray Observations
| Project/Area Number |
07102007
|
|---|
| Research Category |
Grant-in-Aid for Specially Promoted Research
|
| Allocation Type | Single-year Grants |
|---|
| Review Section |
Physics
|
|---|
| Research Institution | Nagoya University |
|---|
Principal Investigator |
YAMASHITA Koujun Dept.of Physics, Nagoya University Professor, 大学院・理学研究科, 教授 (80022622)
|
|---|
| Co-Investigator(Kenkyū-buntansha) |
NAMBA Yoshiharu Chubu University, Faculty of Engineering, Professor, 工学部, 教授 (40029129)
TAWARA Yuzuru Dept.of Physics, Nagoya University Associate Professor, 大学院・理学研究科, 助教授 (10135296)
KUNIEDA Hideyo Dept.of Physics, Nagoya University Associate Professor, 大学院・理学研究科, 助教授 (00126856)
|
|---|
| Project Period (FY) |
1999 – 2002
|
| Keywords | Cluster of Galaxies / X-Ray Imaging / X-Ray Spectrum / The Hubble Constant / Plasma Temperature / X-Ray Telescope / Multilayr Supermirror / Multilayr Grating |
|---|
| Research Abstract |
X-ray images and spectra of nearly 100 clusters of galaxies observed by ASCA were analyzed to investigate their structure and evolution. It was found that isothermal well-relaxed clusters would be ongoing mergers by the analysis of X-ray surface brightness and plasma temperature distributions. Their temperatures are ranged in 5-l2keV over a cluster, which seem to be caused by shock heating of intracluster medium in merging process. The resonance scattering effect of Fe-K lines observed in X-ray spectra plays an importnat role to determine Fe and Ni abundance, which results in increasing by a factor of two at maximum and four, respectively. The Hubble constant was derived to be 60+/-2Okm/sec/Mpc by using Sunyaev-Zel'dovich clusters (z=0.ll-0.54). It was also found that non-thermal point-like objects would exist in sevearl clusters. This is an important evidence for hard X-ray observations.
Development of X-ray telescopes with high efficiency, wide energy range and good angular resolution was performed in great success. In particular, hard X-ray telescopes were designed and constructed by using Pt/C multilayer supermirrors with periodic length of 50-36 A and and 26 layer pairs deposited on thin foil replicated mirrors. The reflectivity was obtained to be 30% in the energy range 25-35kV at the grazing angle of O.3deg. The angular resolution is found to be comparable to that for X-rays of 4.5keV.This is the first demonstration of hard X-ray telescopes in the world. It is promising to open up a new window for X-ray observations and to explore unknown objects. We have also developed multilayer gratings used for spectroscopic observations in the energy of l-lOkeV.Their reflectivity and spectral resolution are obtained to be >20% and >100, respectively.
|
