Are z ~ 5 quasars found in the most massive high-redshift overdensities??
Are z ~ 5 quasars found in the most massive high-redshift overdensities??
复制标题
z ~ 5 类星体是否在最大质量的高红移超密度中发现？
DOI：
10.1093/mnras/stt642
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发表时间：
2013
影响因子：
4.8
通讯作者：
Husband K
中科院分区：
文献类型：
--
作者：
Husband K
发光的高红移类星体(类星体)被认为存在于年轻宇宙中最大质量的暗物质光晕中。因此，它们很可能是早期星系聚集的偏向、过密区域的标志，这些区域最终会成长为较低红移宇宙中所看到的群体和星系团。在这篇文章中，我们探索了∼5类星体周围的星系团，这是由莱曼破裂星系(LBGS)追踪的。我们使用与ESO远程星系调查(ERGS)相同的光学成像和光谱技术来瞄准三个类星体的视场，ERGS成功地识别了LBGS的单个星系团结构。我们利用ERGS中红移聚集的统计数据表明，这三个场中有两个场在类星体红移处显示出显著的LBGS聚集。在LBGS中，仅从成像来看，这两个场都不是明显过密集的；这可能是以前仅对高红移类星体环境进行成像研究给出模糊结果的原因。这一结果表明，∼5时的发光类星体通常位于密度过高的区域。最丰富的类星体场包含至少九个红移相同的光谱确认天体，包括类星体本身，七个LBGS和第二个较弱的类星体。虽然这是一个非常强烈的聚集在∼5的观测信号，但它的强度与在‘空白天空’Ergs场中发现的两个结构中看到的相似。这表明，虽然密度过高，但类星体环境并不比在红移时可以识别的其他结构更极端。在这项工作和ERGS中发现的三个最丰富的结构具有与原星系团预期一致的性质，很可能代表了当今大规模星团和星系团建立的早期阶段。
Luminous high-redshift quasars (QSOs) are thought to exist within the most massive dark matter haloes in the young Universe. As a consequence, they are likely to be markers for biased, overdense regions where early galaxies cluster, regions that eventually grow into the groups and clusters seen in the lower redshift Universe. In this paper, we explore the clustering of galaxies aroundz∼ 5 QSOs as traced by Lyman break galaxies (LBGs). We target the fields of three QSOs using the same optical imaging and spectroscopy techniques as used in the ESO Remote Galaxy Survey (ERGS), which was successful in identifying individual clustered structures of LBGs. We use the statistics of the redshift clustering in ERGS to show that two of the three fields show significant clustering of LBGs at the QSO redshifts. Neither of these fields is obviously overdense in LBGs from the imaging alone; a possible reason why previous imaging-only studies of high redshift QSO environments have given ambiguous results. This result shows that luminous QSOs atz∼ 5 are typically found in overdense regions. The richest QSO field contains at least nine spectroscopically confirmed objects at the same redshift, including the QSO itself, seven LBGs and a second fainter QSO. While this is a very strong observational signal of clustering atz∼ 5, it is of similar strength to that seen in two structures identified in the ‘blank sky’ ERGS fields. This indicates that, while overdense, the QSO environments are not more extreme than other structures that can be identified at these redshifts. The three richest structures discovered in this work and in ERGS have properties consistent with that expected for protoclusters and likely represent the early stages in the build-up of massive current-day groups and clusters.