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外文期刊>The Astrophysical journal
>The WARPS Survey. III. The Discovery of an X-Ray Luminous Galaxy Cluster at z = 0.833 and the Impact of X-Ray Substructure on Cluster Abundance Measurements
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The WARPS Survey. III. The Discovery of an X-Ray Luminous Galaxy Cluster at z = 0.833 and the Impact of X-Ray Substructure on Cluster Abundance Measurements
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机译：WARPS调查。三， Z = 0.833的X射线发光银河星团的发现以及X射线子结构对星团丰度测量的影响
The Wide Angle ROSAT Pointed Survey team reviews the properties and history of the discovery of Cl J0152.7-1357, an X-ray luminous, rich cluster of galaxies at a redshift of z = 0.833. At LX = 8 × 1044 h ergs s-1 (0.5-2.0 keV) Cl J0152.7-1357 is the most X-ray luminous cluster known at redshifts z 0.55. The high X-ray luminosity of the system suggests that massive clusters may begin to form at redshifts considerably greater than unity. This scenario is supported by the high degree of optical and X-ray substructure in Cl J0152.7-1357, which is similarly complex as that of other X-ray-selected clusters at comparable redshift and consistent with the hypothesized picture of cluster formation by mass infall along large-scale filaments. X-ray emission from Cl J0152.7-1357 was detected already in 1980 with the Einstein IPC. However, because the complex morphology of the emission caused its significance to be underestimated, the corresponding source was not included in the cluster sample of the Einstein Extended Medium-Sensitivity Survey (EMSS) and hence was not previously identified. Simulations of the EMSS source detection and selection procedure performed by us suggest a general, mild bias of the EMSS cluster sample against X-ray luminous clusters with pronounced substructure. If highly unrelaxed, merging clusters are common at intermediate-to-high redshift (as is suggested by the current data), they could create a bias in some samples as the morphological complexity of mergers may cause them to fall below the flux limit of surveys that make the implicit or explicit assumption of a unimodal spatial source geometry. Conversely, the enhanced X-ray luminosity of mergers might cause them to, temporarily, rise above the flux limit. Either effect could lead to erroneous conclusions about the evolution of the comoving cluster space density. A high fraction of morphologically complex clusters at high redshift would also call into question the validity of evolutionary studies (and, specifically, cosmological conclusions) which implicitly or explicitly assume that the systems under investigation are virialized.
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机译：广角ROSAT指向调查小组审查了发现的J J102.7-1357的性质和历史，这是X射线发光的丰富星系团，其红移为z = 0.833。在LX = 8×1044 h ers s-1（0.5-2.0 keV）时，Cl J0152.7-1357是红移z> 0.55时已知的最X射线发光簇。该系统的高X射线发光度表明，大的星团可能会以远大于单位的红移开始形成。 Cl J0152.7-1357中高度的光学和X射线子结构支持了这种情况，该结构与其他X射线选择的星团在相当的红移下具有相似的复杂性，并且与通过大量细丝沿质量下落。 1980年，爱因斯坦IPC已检测到Cl J0152.7-1357发出的X射线。但是，由于排放物的复杂形态导致其重要性被低估，因此，相应的排放源未包含在爱因斯坦扩展中度敏感性调查（EMSS）的群集样本中，因此以前没有得到确认。由我们执行的EMSS源检测和选择程序的仿真表明，EMSS簇样品相对于具有明显子结构的X射线发光簇一般偏向温和。如果高度放松的合并集群在中到高红移时很常见（如当前数据所示），则它们可能会在某些样本中产生偏差，因为合并的形态复杂性可能会导致它们低于调查的流量极限对单峰空间源几何进行隐式或显式假设。相反，合并产生的X射线增强的亮度可能会导致它们暂时超过流量限制。两种效应都可能导致关于共同移动的簇空间密度演化的错误结论。在高红移状态下，很大一部分形态复杂的簇也将质疑进化研究（尤其是宇宙学结论）的有效性，这些研究隐含或明确地假定所研究的系统已被病毒化。
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