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arXiv 1406.2702astro-ph.COastro-ph.GA
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Abell 2744的严格自由曲面透镜模型迎接哈勃前沿场的挑战

A Rigorous Free-form Lens Model of Abell 2744 to Meet the Hubble Frontier Fields Challenge

Daniel Lam, Tom Broadhurst, Jose M. Diego, Jeremy Lim, Dan Coe, Holland C. Ford, Wei Zheng

摘要:

哈勃前沿场(HFF)对最强大的透镜星系团的成像提供了对最放大的遥远星系的访问。挑战在于构建能够描述这些复杂的大规模合并集群的透镜模型,以便能够可靠地识别单个透镜系统,并准确地导出其固有特性。我们应用自由形式的透镜方法(WSDG+)的A2744,提供一个模型独立的地图的集群质量,放大率和几何距离估计多透镜源。我们同时解决一个平滑的集群组件上的像素网格,连同本地偏转的集群成员星系。结合模型预测和测光红移测量,我们修正并完成了最近声称的几个系统,并确定了4个新系统-总共65张图像,涵盖了红移范围为1.4<z<9.8的21个系统。重建的质量显示出在X射线中可以看到大量热等离子体的方向上的小增强。我们比较光度红移与“几何红移”,发现一个高层次的自我一致性。我们发现预测和观测到的通量之间非常吻合-最佳拟合斜率为0.999+-0.013和RMS为~0.25等,表明我们对透镜背景星系的放大校正是非常可靠的。有趣的是,很少有多透镜星系被检测到超过z~7.0,尽管HFF滤波器允许高放大率和z~11.5的极限红移。有了额外的HFF集群,我们可以更好地研究任何明显的高Z赤字的可扩展性,具有潜在的重要意义的再电离时代和暗物质的性质。

英文摘要:

Hubble Frontier Fields (HFF) imaging of the most powerful lensing clusters provides access to the most magnified distant galaxies. The challenge is to construct lens models capable of describing these complex massive, merging clusters so that individual lensed systems can be reliably identified and their intrinsic properties accurately derived. We apply the free-form lensing method (WSLAP+) to A2744, providing a model independent map of the cluster mass, magnification, and geometric distance estimates to multiply-lensed sources. We solve simultaneously for a smooth cluster component on a pixel grid, together with local deflections by the cluster member galaxies. Combining model prediction with photometric redshift measurements, we correct and complete several systems recently claimed, and identify 4 new systems - totalling 65 images of 21 systems spanning a redshift range of 1.4<z<9.8. The reconstructed mass shows small enhancements in the directions where significant amounts of hot plasma can be seen in X-ray. We compare photometric redshifts with "geometric redshifts", finding a high level of self-consistency. We find excellent agreement between predicted and observed fluxes - with a best-fit slope of 0.999+-0.013 and an RMS of ~0.25 mag, demonstrating that our magnification correction of the lensed background galaxies is very reliable. Intriguingly, few multiply-lensed galaxies are detected beyond z~7.0, despite the high magnification and the limiting redshift of z~11.5 permitted by the HFF filters. With the additional HFF clusters we can better examine the plausibility of any pronounced high-z deficit, with potentially important implications for the reionization epoch and the nature of dark matter.

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