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arXiv 0806.0861astro-ph
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用XMM-牛顿远星系团计划研究宇宙演化:z>~1的X射线发光星系团及其星系群

Studying Cosmic Evolution with the XMM-Newton Distant Cluster Project: X-ray Luminous Galaxy Clusters at z>~1 and their Galaxy Populations

Rene Fassbender

摘要:

研究z>~1的X射线发光星系团,为宇宙中最大的维里化结构、热ICM形式的重子物质、它们的星系群以及暗能量的影响的演化研究提供了一个基本的限制。这项工作的主要目的是为XMM-牛顿遥远星团计划(XDCP)建立观测基础。这项新的偶然发现的调查集中在z>1的最遥远的系统上,基于扩展X射线源的选择,通过双波段成像将它们识别为星系团,以及最终的光谱确认。通过对80度^2深XMM-牛顿存档数据的分析,近1000个扩展源被选为聚类候选者,其中75%可以很容易地被识别为z<~0.6的系统。对于剩下的250个遥远的候选星系团,采用了一种新的确认和红移估计策略,基于Z和H波段测光和观测到的早型星系团的Z-H红序列颜色。通过对25%的样品的观测,在光度红移z>~0.9处发现了超过20个X射线团簇。新的Z-H方法允许在0.2<~z<~1.5的前所未有的红移基线上进行团簇样本研究。通过对红序列颜色演化的观测与模型预测的比较,可以将早型星系的形成时代限定为zf =4.2 ± 1.1,证实了它们的古老年龄。对63个BCGs的H波段光度演化的初步研究首次提供了直接的观测迹象,表明最大质量的星系团星系自z~1.5以来已经增加了一倍。在最后9 Gyr中组装BCG的发现现在与最新的模拟定性一致。

英文摘要:

Investigating X-ray luminous galaxy clusters at z>~1 provides a fundamental constraint on evolutionary studies of the largest virialized structures in the Universe, the baryonic matter in form of the hot ICM, their galaxy populations, and the effects of Dark Energy. The main aim of this work is to establish the observational foundation for the XMM-Newton Distant Cluster Project (XDCP). This new serendipitous survey is focused on the most distant systems at z>1, based on the selection of extended X-ray sources, their identification as clusters via two-band imaging, and their final spectroscopic confirmation. Almost 1000 extended sources were selected as cluster candidates from the analysis of 80 deg^2 of deep XMM-Newton archival data, of which 75% could be readily identified as systems at z<~0.6. For the remaining 250 distant cluster candidates a new strategy for their confirmation and redshift estimates was adopted, based on Z- and H-band photometry and the observed Z-H red-sequence color of early-type cluster galaxies. From observations of 25% of the sample, more than 20 X-ray clusters were discovered at a photometric redshift of z>~0.9. The new Z-H method has allowed a cluster sample study over an unprecedented redshift baseline of 0.2<~z<~1.5. From a comparison of the observed color evolution of the red-sequence with model predictions, the formation epoch of early-type galaxies could be constrained as z_f=4.2+-1.1, confirming their well-established old age. The preliminary investigation of the H-band luminosity evolution of 63 BCGs provides for the first time direct observational indications that the most massive cluster galaxies have doubled their stellar mass since z~1.5. The finding that BCGs were assembled in the last 9Gyr is now in qualitative agreement with the latest simulations.

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