标题： 钱德拉对化石系统X射线气体性质的研究 显示英文标题

标题： Chandra Studies of the X-ray Gas Properties of Fossil Systems

摘要： 我们基于\chandra 观测研究了文献中提出的十个被归类为“化石系统（FS）”的星系群和星系团。根据$M_{500}-T$和$L_{\rm X}-T$关系，FS 的气体性质在物理上并不区别于普通星系群或星系团。我们还首次研究了$f_{\rm gas,~2500}-T$关系，并发现 FS 与普通系统表现相同。FS 在$0.1r_{200}$范围内的气体密度为$\sim 10^{-3}$cm$^{-3}$，与星系团处于同一数量级。 FSs 中的熵在$0.1r_{200}$（$S_{0.1r_{200}}$）内系统性地低于普通星系群，这与先前的报告一致，但我们发现它们的$S_{0.1r_{200}}-T$关系更类似于星系团。 FSs 的推导出的质量分布与$(0.1-1)r_{200}$的 Navarro、Frenk 和 White 模型一致，并且标量半径$r_{\rm s}$和特征质量密度$ta_{\rm c}$之间的关系表明 FSs 的暗物质晕具有自相似性。 FSs的$r_{\rm s}$和$ta_{\rm c}$范围也接近星系团的范围。因此，FSs与星系团有更多的共同特征。特殊诞生地使FSs成为一种独特的星系系统类型。 显示英文摘要

摘要： We study ten galaxy groups and clusters suggested in the literature to be "fossil system (FS)" based on \chandra\ observations. According to the $M_{500}-T$ and $L_{\rm X}-T$ relations, the gas properties of FSs are not physically distinct from ordinary galaxy groups or clusters. We also first study the $f_{\rm gas,~2500}-T$ relation and find that the FS exhibits same as ordinary systems. The gas densities of FSs within $0.1r_{200}$, are $\sim 10^{-3}$ cm$^{-3}$, which is the same order as galaxy clusters. The entropies within $0.1r_{200}$ ($S_{0.1r_{200}}$) of FSs are systematically lower than those in ordinary galaxy groups which is consistent with previous report, but we find their $S_{0.1r_{200}}-T$ relation is more similar to galaxy clusters. The derived mass profiles of FSs are consistent with the Navarro, Frenk, \& White model in $(0.1-1)r_{200}$, and the relation between scale radius $r_{\rm s}$ and characteristic mass density $ta_{\rm c}$ indicates the self-similarity of dark matter halos of FSs. The range of $r_{\rm s}$ and $ta_{\rm c}$ of FSs are also close to those of galaxy clusters. Therefore, FSs share more common characteristics with galaxy clusters. The special birth place of the FS makes it as a distinct galaxy system type.