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arXiv 1111.3642astro-ph.CO
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星系团WARPJ1415 .1+3612在z=1时的深钱德拉观测:一个高红移的演化冷核星系团

Deep Chandra observation of the galaxy cluster WARPJ1415.1+3612 at z=1: an evolved cool-core cluster at high-redshift

Joana S. Santos, Paolo Tozzi, Piero Rosati, Mario Nonino, Gabriele Giovannini

摘要:

使用最深(370千秒)的钱德拉观测高红移星系团,我们进行了详细的描述内集群介质(ICM)的WARPJ 1415.1 +3612在z=1.03。我们还探讨了ICM的核心属性和最亮的星系团(BCG)的无线电/光学特性之间的联系。我们进行空间分辨分析的ICM,以获得温度,金属丰度和表面亮度的配置文件。利用反投影的温度和密度分布,我们精确地导出了不同密度下的团簇质量。除了X射线数据,我们使用档案无线电VLA成像和光学GMOS光谱的中央星系,调查中央星系和ICM之间的反馈。X射线光谱分析表明,一个显着的温度下降到集群中心,预测值Tc = 4.6 \pm 0.4 keV,和一个非常高的中心铁丰度峰,Zc= 3.6 Zsun。中心冷却时间小于0.1 Gyr,熵等于9.9 keV cm ~ 2。我们在BCG的光谱中检测到一条强的[OII]发射线,其等效宽度为-25,由此我们推导出恒星形成率在2 - 8 Msun/yr范围内。VLA数据揭示了一个与BCG一致的中央射电源和一个范围为80 kpc的微弱的单侧喷流状特征。分析表明,WARPJ 1415有一个发育良好的冷核,其ICM特性与当地宇宙中发现的相似。它的性质和在中央星系中发现的反馈活动在光学和无线电波段的明确迹象表明,反馈过程已经建立在z~1。此外,一个强金属丰度峰的存在表明,在z > 1时,中央星系的恒星形成过程已经迅速地富集了中央区域。

英文摘要:

Using the deepest (370 ksec) Chandra observation of a high-redshift galaxy cluster, we perform a detailed characterization of the intra-cluster medium (ICM) of WARPJ1415.1+3612 at z=1.03. We also explore the connection between the ICM core properties and the radio/optical properties of the brightest cluster galaxy (BCG). We perform a spatially resolved analysis of the ICM to obtain temperature, metallicity and surface brightness profiles. Using the deprojected temperature and density profiles we accurately derive the cluster mass at different overdensities. In addition to the X-ray data, we use archival radio VLA imaging and optical GMOS spectroscopy of the central galaxy to investigate the feedback between the central galaxy and the ICM. The X-ray spectral analysis shows a significant temperature drop towards the cluster center, with a projected value of Tc = 4.6 \pm 0.4 keV, and a remarkably high central iron abundance peak, Zc= 3.6 Zsun. The central cooling time is shorter than 0.1 Gyr and the entropy is equal to 9.9 keV cm2. We detect a strong [OII] emission line in the optical spectra of the BCG with an equivalent width of -25 Å, for which we derive a star formation rate within the range 2 - 8 Msun/yr. The VLA data reveals a central radio source coincident with the BCG and a faint one-sided jet-like feature with an extent of 80 kpc. The analysis presented shows that WARPJ1415 has a well developed cool core with ICM properties similar to those found in the local Universe. Its properties and the clear sign of feedback activity found in the central galaxy in the optical and radio bands, show that feedback processes are already established at z~1. In addition, the presence of a strong metallicity peak shows that the central regions have been promptly enriched by star formation processes in the central galaxy already at z > 1.

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