蜘蛛网中苍蝇的SINFONI视图：一个正在形成的星系团
A SINFONI view of flies in the Spiderweb: a galaxy cluster in the making
摘要：
z~2.2的高z射电星系PKS 1138-262的环境是形成星系团的最好例子。我们使用深SINFONI数据进行了详细的研究，在60千秒差距的无线电核心的星系的运动学，我们将其链接到megaparsec尺度上的原星系团的运动学。光发射谱线的识别表明，11个星系的红移的原星系团。原星系团核心的线辐射源密度比大尺度环境高出一个数量级以上。这意味着在delta_m~70的核心有一个物质过密度区，类似于局部星系团的外围。已确认的卫星星系的速度分布显示出一个宽的双峰速度结构，sigma=1360+/-206 km/s。在以前针对大尺度原星系团结构的研究中发现了类似的广泛的双峰分布，这表明一个共同的过程作用于小尺度和大尺度。包括所有光谱证实的原星系团，发现其速度色散为1013+/-87km/s.我们表明原星系团可能与哈勃流解耦，是一个动态演化的结构.与Millenium模拟结果的比较表明，原星系团的速度分布与z~2处质量最大的晕的速度分布一致，但根据动力学参数和X射线光度，我们排除了原星系团是完全维里化结构的可能性。与千禧年模拟中合并晕的比较表明，在蜘蛛网星系及其周围观察到的结构最好解释为两个大质量晕合并的结果。我们认为，这种合并可以导致在原星系团核心的恒星形成和活动星系核活动的增加，并可能是一个重要的阶段，在大规模的cD星系的演化。
英文摘要：
The environment of the high-z radio galaxy PKS 1138-262 at z~2.2 is a prime example of a forming galaxy cluster. We use deep SINFONI data to perform a detailed study of the kinematics of the galaxies within 60 kpc of the radio core and we link this to the kinematics of the protocluster on the megaparsec scale. Identification of optical emission lines shows that 11 galaxies are at the redshift of the protocluster. The density of line emitters is more than an order of magnitude higher in the core of the protocluster than the larger scale environment. This implies a matter overdensity in the core of delta_m~70 which is similar to the outskirts of local galaxy clusters. The velocity distribution of the confirmed satellite galaxies shows a broad, double-peaked velocity structure with sigma=1360+/-206 km/s. A similar broad, double-peaked distribution was found in a previous study targeting the large scale protocluster structure, indicating that a common process is acting on both small and large scales. Including all spectroscopically confirmed protocluster galaxies, a velocity dispersion of 1013+/-87 km/s is found. We show that the protocluster has likely decoupled from the Hubble flow and is a dynamically evolved structure. Comparison to the Millenium simulation indicates that the protocluster velocity distribution is consistent with that of the most massive haloes at z~2, but we rule out that the protocluster is a fully virialized structure based on dynamical arguments and its X-ray luminosity. Comparison to merging haloes in the Millennium simulation shows that the structure as observed in and around the Spiderweb galaxy is best interpreted as being the result of a merger between two massive haloes. We propose that this merger can result in an increase in star formation and AGN activity in the protocluster core and is possibly an important stage in the evolution of massive cD galaxies.
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