阿贝尔370重访：翻新哈勃成像的第一个强透镜集群
Abell 370 revisited: refurbished Hubble imaging of the first strong lensing cluster
摘要：
我们提出了一个强大的透镜分析的星系团阿贝尔370（z=0.375）的基础上获得的早期释放观测（ERO）的一部分，随后哈勃服务任务#4的最新的ARMACS图像。早在1987年，Abell 370中的巨大引力弧（z=0.725）是第一批证据之一，表明大质量星系团的密度足以充当强引力透镜。新的观测结果详细揭示了它的盘状形态，我们表明它可以被解释为一个复杂的五像结构，总放大倍数为32+/-4。此外，高分辨率的射电望远镜信息使我们能够识别10个多重成像的背景星系。对于z=2的源红移，我们得到了平均爱因斯坦半径RE=39+/-2”，对应于质量M（<RE）= 2.82+/-0.15 1 e ~（14）Msol和M（<250 kpc）=3.8+/-0.2 1 e ~（14）Msol，与Subaru弱透镜测量结果吻合得很好。典型的质量模型误差小于5%，与之前的透镜分析相比，改进了3倍。Abell 370质量分布被证实是双峰的，暗物质、X射线气体和恒星质量之间的偏移很小。将这些信息与速度分布相结合，揭示了阿贝尔370可能是两个质量相等的星团沿着视线合并，解释了有效产生强透镜效应所需的非常高的质量密度。这些新的观察结果强调了多图像识别的重要性，这是确定准确质量模型的关键。非常大的爱因斯坦半径使Abell 370成为通过中央区域的强放大来寻找高红移星系的最佳星系团之一。
英文摘要：
We present a strong lensing analysis of the galaxy cluster Abell 370 (z=0.375) based on the recent multicolor ACS images obtained as part of the Early Release Observation (ERO) that followed the Hubble Service Mission #4. Back in 1987, the giant gravitational arc (z=0.725) in Abell 370 was one of the first pieces of evidence that massive clusters are dense enough to act as strong gravitational lenses. The new observations reveal in detail its disklike morphology, and we show that it can be interpreted as a complex five-image configuration, with a total magnification factor of 32+/-4. Moreover, the high resolution multicolor information allowed us to identify 10 multiply imaged background galaxies. We derive a mean Einstein radius of RE=39+/-2" for a source redshift at z=2, corresponding to a mass of M(<RE) = 2.82+/-0.15 1e14 Msol and M(<250 kpc)=3.8+/-0.2 1e14 Msol, in good agreement with Subaru weak-lensing measurements. The typical mass model error is smaller than 5%, a factor 3 of improvement compared to the previous lensing analysis. Abell 370 mass distribution is confirmed to be bi-modal with very small offset between the dark matter, the X-ray gas and the stellar mass. Combining this information with the velocity distribution reveals that Abell 370 is likely the merging of two equally massive clusters along the line of sight, explaining the very high mass density necessary to efficiently produce strong lensing. These new observations stress the importance of multicolor imaging for the identification of multiple images which is key to determining an accurate mass model. The very large Einstein radius makes Abell 370 one of the best clusters to search for high redshift galaxies through strong magnification in the central region.
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