| Budget Amount *help |
¥7,900,000 (Direct Cost: ¥7,900,000)
Fiscal Year 1998: ¥1,700,000 (Direct Cost: ¥1,700,000)
Fiscal Year 1997: ¥1,600,000 (Direct Cost: ¥1,600,000)
Fiscal Year 1996: ¥4,600,000 (Direct Cost: ¥4,600,000)
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| Research Abstract |
Although we found no evidence of CG evolution in the k_BT-L_X relation in the redshift range of z=0.0 - 1.0, nor in the k_BT-M_<gas>, k_BT-M_<Fe>, k_BT-A_<Fe> relation in z<0.6, some hints of evolution at z>0.6 are found ; the gas masses of the most distant cluster AXJ20I9+1127 at z-1.0 are significantly lower than those of the other CGs with the same gas temperature, the iron masses of the cluster is similar to that of nearby cluster.
We observed starburst galaxy M82 with ASCA in order to investigate the ejection mechanism of metal rich gas. The X-rays in the 0.5-10 keV band exhibit a thin thermal spectrum with emission lines from highly ionized magnesium, silicon, and sulfur, as well as a hard tail extending to higher than l0keV energy. The soft X-rays are spatially extended, while the hard X-rays show an unresolved point-like structure with possible a long-term flux variability. The flux ratio of the emission lines and the spatially extended structure in the low-energy band indicate
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that at least two-temperature thin thermal plasmas are present. The abundances of the oxygen, neon, magnesium, silicon, sulfur, and iron in the thin thermal plasmas are found to be significantly lower than the cosmic value.
The spectrum of the hard component, which is spatially unresolved, is well represented by an absorbed thermal bremsstrahlung, or an absorbed power-law model. However the origin of the hard component was unclear. Thus, we made a monitoring observation with ASCA in 1996. Although the X-ray flux of the soft and medium components remained constant, a significant time variability of the hard component was found between 3 <<1>> 10^<40> erg/s and 1 <<1>> 10^<41> erg/s at various time scales from 10 ks to a month. The temperature or photon index of the hard component also changed. We proved that the spatial position of the hard component is the center of M82. The spectrum of the variable source obtained by subtracting the spectrum of the lowest state from the highest state suggests the strong absorption of NH- 10^<22> cm^<-2>, which means the variable source is embedded in the center of M82. All these suggest that a low-luminosity AGN exists in M82. Less
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