Abstract
Clusters of galaxies are the largest observed objects in the sky which are gravitationallybound, and the brightest X-ray emitters. Observed X-ray spectra of clusters of galaxies
consist of continuum emission components and lines of highly ionized heavy elementsfrom a thin hot plasma in collisional ionization equilibrium (CIE). The existence of lines
revealed that the intracluster medium (ICM) is a mixture of metal-poor primordial gas
and metal-rich processed gas. The distributions of heavy elements from line analysis isa clue to investigate the chemical evolution of galaxy clusters. There are such schemes
as which heavy elements are ejected into the interstellar space through supernova orstellar mass loss and injected into the intra-cluster space through ram-pressure strippingor galactic winds.
The ICM has a small optical depth, that is, optically thin for continuum because theThomson scattering optical depth Th is much less than unity, typically 1002 . However
this is not the case for the stronger resonance lines. A resonance-line photon is scatteredby the ions in the same state of ionization as an ion emitting the photon, and has relatively
large absorption oscillator strength (e.q. f12 > 0.1). Then, it is re-emitted, generally ina di erent direction. Therefore, the optical depth of the resonance lines is hundreds or
thousands times larger than the Th .
The resonance lines are scattered mainly in the center of a cluster where the density
is high, and are observed to be suppressed. The di usion of the photons with respect tofrequency tends to form the saddle-shaped line pro les. On the other hand, the suppressedcomponent is observed to be a signi cant enhancement in outer part of cluster. Eventually
the total intensity over the whole cluster is not changed.
149 clusters of galaxies, Virgo Cluster and Perseus Cluster and so on were observedwith ASCA satellite, which is capable for imaging spectroscopy. From the spectra integrated over annual rings whose center is located at the cluster center, temperatures are
con rmed to be lower at the center of many nearby clusters (redshift < 0.1) with factor< 2, for example, A496 and Perseus cluster. On the other hand, some of distant clusters(redshift > 0.1) are suggested to have radial temperature decline with factor less than2, for example, A2204 and A1689. Based on the line features, especially iron K line,abundances are enhanced at the center of A496, A3158, M87 and Perseus cluster and soon.
Among the observed lines, iron K lines are found separately from K lines by the GIS
detectors, and He-like and H-like iron K lines can be distinguished by at SIS detector.
I called them K -Blend, K -Blend, He-K -Blend and H-K -Blend. However K -Blend1

includes Ni K lines. I estimated the intensities and the ratios (K -Blend / K -Blend R1, He-K -Blend / H-K -Blend  R2 ) of these lines. According to the results of GISanalysis, 80 % of clusters suggest that R1 of cluster center tends to be smaller than that
expected from optically thin plasma model and to increase as the radius. The results ofSIS analysis show that R2 of each cool clusters (kT < 6 keV ) is smaller than the modelvalue. Furthermore, in order to get the sucient photon statistics, 83 bright clusters ofgalaxies are divided into 4 groups with respect to temperature (1{3 keV , 3{6 keV , 6{9keV , > 9 keV ), all spectra of each groups are summed up, after the correction of theredshift. These spectra make it clear that these trends of ratios, R1 and R2 , are univeral
for clusters of galaxies. These results are consistent with the e ect of resonance scattering.
On the other hand, He-K -Blend and H-K -Blend are separated in the statistical line
analysis of SIS spectra. As the three new ratios (He-K -Blend / H-K -Blend  R3 , HeK -Blend / He-K -Blend  R4 and H-K -Blend / H-K -Blend  R5 ) were also obtained,the line analysis could be done in detail.
In order to understand these observed ratios, I simulated 41 lines (He-K -Blend andH-K -Blend include 7 and 16 lines, and K -Blend consists of 18 lines.) in energy range
between 6.4{8.2 keV in consideration of the e ect of the resonance scattering, using Monte
Carlo method. Then, I got the line intensity ratios R1 and R2 , and compared them withobserved line intensity ratios.
As a consequence, observed R1 and R2 of hot clusters (kT > 6 keV ) can be explainedby the resonance scattering. The obtained  of He-like iron K line of cluster center is 2{
4. This indicates abundances estimated from K lines without considering the resonancescattering is factor  2 smaller than real values at the cluster center.
Observed R1 and R2 of the cool cluster (kT < 3 keV ) are smaller than the values
obtained by simulation of the resonance scattering, though the trend is consistent withthe e ect of the resonance scattering. Moreover the R1 estimated from spectrum of thewhole cluster is also smaller than the model ratio. It is needed to consider other causes,
for example, some more characteristics of cluster such as size or to reform the atomic
data. Especially, as one of them, the contamination fo Nickel K lines for cool cluster areconsidered. The R3 , R4 and R5 ratios suggest the existence of hot plasma or contaminationof K and K.

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