Study of Poor Cluster of Galaxies with X-ray

用ASCA对早期类型星系的观测得到了以下新结果：1.X射线谱由低温等离子体成分和硬成分组成。2.硬组分以LMXB为主。3.重元素的丰度约为太阳的一半。4.X射线光度与等离子体组分温度呈正相关。对室女座星系团中心M87的ASCA观测表明：1.M87的X射线发射等离子体由一个受星系团引力约束的高温分量和一个受M87.2约束的低温分量组成。贫星团所含的重金属被认为是从原始星系中喷出的。恒星暴增星系是这种早期星系的原型。对星暴星系M82的观测结果表明：1.预计由II型SN合成的氧谱线很弱。2.铁丰度低。3.另一方面，硅和硫磺含量丰富。4.结果表明，贫星团中金属的来源不能简单地用星暴星系的抛射来解释。对z=0.194的远距离贫星系团MS0839.8的观测结果表明：1.近距离星系团与远距离星系团在温度和X射线光度上没有差别。2.结果表明，从z=0.2到现在，没有发生过强烈的演化。

Following new results were obtained from the observations of early type galaxies with ASCA.1.X-ray spectrum consists of a low temperature plasma component and a hard component. 2.The hard component is dominated by LMXB.3.Abundances of heavy elements are about a half solar value. 4.A positive correlation is seen between X-ray luminosity and temperature of the plasma component. ASCA observation of M87 at the center of the Virgo cluster of galaxies shows as follows ; 1.X-ray emitting plasma in M87 consists of a high temperature component bounded by the cluster gravity and a low temperature component bounded by M87.2.Apparent iron concentration at the M87 center is seen. Heavy metals contained by poor clusters are thought to be ejected from primordial-galaxies. Starburst galaxies are proto-type of such early phase of galaxies. Observations of the starburst galaxy M82 shows following results ; 1.Oxygen lines expected to be synthesized by type II SN are weak. 2.Iron abundance is low. 3.On the other hand, silicon and sulfa are rich. 4.The results indicate that the origin of metals in poor clusters cannot be explained simply by ejection from starburst galaxies. The observation of a distant poor cluster of galaxies MS0839.8 at z=0.194 shows the following results ; 1.No difference on temperature and X-ray luminosity between near and distant clusters is seen. 2.The result implies no strong evolution has not been occurred from z=0.2 until the present.