arXiv 1606.045272016-06-14astro-ph.CO

哈勃前沿场星系团Abell 2744中的异常数量子结构

The Extraordinary Amount of Substructure in the Hubble Frontier Fields Cluster Abell 2744

M. Jauzac, D. Eckert, J. Schwinn, D. Harvey, C. M. Baugh, A. Robertson, S. Bose, R. Massey, M. Owers, H. Ebeling, H. Y. Shan, E. Jullo, J. -P. Kneib, J. Richard… 展开作者

M. Jauzac, D. Eckert, J. Schwinn, D. Harvey, C. M. Baugh, A. Robertson, S. Bose, R. Massey, M. Owers, H. Ebeling, H. Y. Shan, E. Jullo, J. -P. Kneib, J. Richard, H. Atek, B. Clément, E. Egami, H. Israel, K. Knowles, M. Limousin, P. Natarajan, M. Rexroth, P. Taylor, C. Tchernin

备注：: Submitted to MNRAS -- 19 pages, 8 figures, 6 tables
DOI：: 10.1093/mnras/stw2251

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摘要：

本文对大质量星系团Abell 2744（z=0.308）进行了光学/X射线联合分析。我们在星团中心区域的强透镜和弱透镜分析，即，在距离最亮的星系团R<1 Mpc处，揭示了包括主核心在内的八个子结构。所有这些暗物质晕都被探测到，其显著性至少为5西格玛，特征质量在0.5到1.4 × 10 ^{14}Msun之间，R<150 kpc。Merten et al.（2011）和Meidinski et al.（2016）亚结构也被我们检测到。我们测量的主要核心组件的质量略高于先前报道的质量，并将这种差异归因于我们基于哈勃前沿场数据建立的严格约束的强透镜质量模型。XMM-牛顿获得的X射线数据揭示了四个残余核心，其中一个是新发现的，还有三个冲击。与Merten等人（2011）不同，我们发现所有的核心都有黑暗和明亮的对应物。与MXXL模拟中类似质量的星团进行比较，没有发现像阿贝尔2744那样有大量子结构的天体，这证实了阿贝尔2744是一个极端的系统。我们强调，这些属性仍然不构成一个挑战，$Λ$ CDM，因为警告适用于模拟和观测：例如，投影质量测量从引力透镜和有限的分辨率的子晕发现者。我们讨论了Abell 2744对不同暗物质候选者的相容性的影响，最后，测量了暗物质自相互作用截面的新上限，即sigma_{DM} <1.28 cm 2/g（68\% CL），与Harvey等人（2015）的先前结果非常一致。

英文摘要：

We present a joint optical/X-ray analysis of the massive galaxy cluster Abell 2744 (z=0.308). Our strong- and weak-lensing analysis within the central region of the cluster, i.e., at R<1Mpc from the brightest cluster galaxy, reveals eight substructures, including the main core. All of these dark-matter halos are detected with a significance of at least 5sigma and feature masses ranging from 0.5 to 1.4x10^{14}Msun within R<150kpc. Merten et al. (2011) and Medezinski et al. (2016) substructures are also detected by us. We measure a slightly higher mass for the main core component than reported previously and attribute the discrepancy to the inclusion of our tightly constrained strong-lensing mass model built on Hubble Frontier Fields data. X-ray data obtained by XMM-Newton reveal four remnant cores, one of them a new detection, and three shocks. Unlike Merten et al. (2011), we find all cores to have both dark and luminous counterparts. A comparison with clusters of similar mass in the MXXL simulations yields no objects with as many massive substructures as observed in Abell 2744, confirming that Abell 2744 is an extreme system. We stress that these properties still do not constitute a challenge to $Λ$CDM, as caveats apply to both the simulation and the observations: for instance, the projected mass measurements from gravitational lensing and the limited resolution of the sub-haloes finders. We discuss implications of Abell 2744 for the plausibility of different dark-matter candidates and, finally, measure a new upper limit on the self-interaction cross-section of dark matter of sigma_{DM}<1.28cm2/g(68\% CL), in good agreement with previous results from Harvey et al. (2015).

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