具有GROND的X射线选择高红移星系团的第一次同时光学/近红外成像：z=1.1时XMMU J0338 .7+0030的星系群
First simultaneous optical/near-infrared imaging of an X-ray selected, high-redshift cluster of galaxies with GROND: the galaxy population of XMMU J0338.7+0030 at z=1.1
摘要：
XMM-牛顿遥远星系团计划是一个偶然的调查星系团的红移z>=0.8的基础上深档案XMM-牛顿观测。...低重要性的候选高z星系团被安装在2米级望远镜上的七通道成像仪GROND（伽马射线暴光学和近红外探测器）跟踪。...测试用例为XMMU J0338.7+0030，根据对从随访成像中获得的z-H vs H颜色-幅度图的分析，建议其位于z~1.45+/-0.15处。后来的VLT-FORS 2光谱使我们能够识别出四个成员，这使得这个集群的z=1.097+/-0.002。为了更好地了解它的星系人口，我们用GROND对XMMU J0338.7+0030进行了大约6小时的观测。在XMMU J0338.7+0030的3.9 × 4.3平方角分区域中，在所有GROND波段成像的832个低至z '~ 26 AB-mag的非恒星源中，KS波段计数明显超过在~20.5 - 22.5 AB-mag的深场/巡天区域中计算的计数。0.09.具有在1.01 - 1.23范围内的photo-z的GROND源的空间分布和性质证实了X射线源与星系过密度的对应关系，其显著性至少为4.3 sigma。在分光光度学上被归类为椭圆星系的候选成员，在i '-z'与z'的颜色星等图中定义了一个红色的轨迹，这与星系团RDCS J 0910 +5422在z=1.106处的红色序列一致。XMMU J0338.7+0030也有一个更蓝的晚型螺旋和不规则的种群。光度成员之间的星爆填充两个位点，与以前的结果一致。对现有数据集的分析表明XMMU J0338.7+0030是一个z=1.1的低质量星系团（M_200 ~ 1 E14 M_sun）。（节录）
英文摘要：
The XMM-Newton Distant Cluster Project is a serendipitous survey for clusters of galaxies at redshifts z>=0.8 based on deep archival XMM-Newton observations. ... Low-significance candidate high-z clusters are followed up with the seven-channel imager GROND (Gamma-Ray Burst Optical and Near-Infrared Detector) that is mounted at a 2m-class telescope. ... The test case is XMMU J0338.7+0030, suggested to be at z~1.45+/-0.15 from the analysis of the z-H vs H colour-magnitude diagram obtained from the follow-up imaging. Later VLT-FORS2 spectroscopy enabled us to identify four members, which set this cluster at z=1.097+/-0.002. To reach a better knowledge of its galaxy population, we observed XMMU J0338.7+0030 with GROND for about 6 hr. The publicly available photo-z code le Phare was used. The Ks-band number counts of the non-stellar sources out of the 832 detected down to z'~26 AB-mag in the 3.9x4.3 square arcmin region of XMMU J0338.7+0030 imaged at all GROND bands clearly exceed those computed in deep fields/survey areas at ~20.5 - 22.5 AB-mag. The photo-z's of the three imaged spectroscopic members yield z=1.12+/-0.09. The spatial distribution and the properties of the GROND sources with a photo-z in the range 1.01 - 1.23 confirm the correspondence of the X-ray source with a galaxy over-density at a significance of at least 4.3 sigma. Candidate members that are spectro-photometrically classified as elliptical galaxies define a red locus in the i'-z' vs z' colour-magnitude diagram that is consistent with the red sequence of the cluster RDCS J0910+5422 at z=1.106. XMMU J0338.7+0030 hosts also a population of bluer late-type spirals and irregulars. The starbursts among the photometric members populate both loci, consistently with previous results. The analysis of the available data set indicates that XMMU J0338.7+0030 is a low-mass cluster (M_200 ~ 1E14 M_sun) at z=1.1. (Abridged)
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