HUBBLE SPACE TELESCOPE WEAK-LENSING STUDY OF THE GALAXY CLUSTER XMMU J2235.3 − 2557 AT z ∼ 1.4: A SURPRISINGLY MASSIVE GALAXY CLUSTER WHEN THE UNIVERSE IS ONE-THIRD OF ITS CURRENT AGE
HUBBLE SPACE TELESCOPE WEAK-LENSING STUDY OF THE GALAXY CLUSTER XMMU J2235.3 − 2557 AT z ∼ 1.4: A SURPRISINGLY MASSIVE GALAXY CLUSTER WHEN THE UNIVERSE IS ONE-THIRD OF ITS CURRENT AGE
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DOI：
10.1088/0004-637x/704/1/672
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发表时间：
2009-08
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通讯作者：
Myung-Kook Jee;P. Rosati;H. Ford;K. Dawson;C. Lidman;S. Perlmutter;R. Demarco;V. Strazzullo;C. Mullis;H. Böhringer;R. Fassbender
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作者：
Myung-Kook Jee;P. Rosati;H. Ford;K. Dawson;C. Lidman;S. Perlmutter;R. Demarco;V. Strazzullo;C. Mullis;H. Böhringer;R. Fassbender
我们基于深度高级巡天相机图像，对 z ≃ 1.4 星系团 XMMU J2235.3 − 2557 进行弱透镜分析。尽管透镜的高红移给观测带来了挑战，但我们还是检测到了 ≳8σ 水平的大量透镜信号。这种清晰的检测部分是由于簇的高质量而实现的，这通过我们对簇质量的参数和非参数估计得到了验证。假设星团遵循 Navarro-Frenk-White 质量分布，我们估计 r = 1 Mpc 内星团的投影质量为 (8.5 ± 1.7) × 1014 M☉，其中误差条包括剪切分布的统计不确定性、可能的插入背景结构的影响、浓度参数的散射以及我们对背景星系平均红移的估计误差。最近用钱德拉测量到的星团的高 X 射线温度 8.6+1.3−1.2 keV 与这种高透镜质量一致。当我们采用 1σ 下限作为质量阈值并使用威尔金森微波各向异性探测器 5 年（WMAP5）结果所支持的宇宙学参数时，在 11 平方度巡天中 z ≳ 1.4 处类似质量星团的预期数量为 N ∼ 5 × 10−3。因此，在勘测体积内发现星团是一个罕见事件，概率≲1%，并且可能为我们目前对标准宇宙学模型内星团形成的理解开启新的场景。
We present a weak-lensing analysis of the z ≃ 1.4 galaxy cluster XMMU J2235.3 − 2557, based on deep Advanced Camera for Surveys images. Despite the observational challenge set by the high redshift of the lens, we detect a substantial lensing signal at the ≳8σ level. This clear detection is enabled in part by the high mass of the cluster, which is verified by our both parametric and non-parametric estimation of the cluster mass. Assuming that the cluster follows a Navarro–Frenk–White mass profile, we estimate that the projected mass of the cluster within r = 1 Mpc is (8.5 ± 1.7) × 1014 M☉, where the error bar includes the statistical uncertainty of the shear profile, the effect of possible interloping background structures, the scatter in concentration parameter, and the error in our estimation of the mean redshift of the background galaxies. The high X-ray temperature 8.6+1.3−1.2 keV of the cluster recently measured with Chandra is consistent with this high lensing mass. When we adopt the 1σ lower limit as a mass threshold and use the cosmological parameters favored by the Wilkinson Microwave Anisotropy Probe 5-year (WMAP5) result, the expected number of similarly massive clusters at z ≳ 1.4 in the 11 square degree survey is N ∼ 5 × 10−3. Therefore, the discovery of the cluster within the survey volume is a rare event with a probability ≲1% and may open new scenarios in our current understanding of cluster formation within the standard cosmological model.