A Unique Small-Scale Gravitational Arc in A1201
A Unique Small-Scale Gravitational Arc in A1201
复制标题
A1201 中独特的小尺度引力弧
DOI：
10.1086/381193
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发表时间：
2003
期刊：
影响因子：
--
通讯作者：
P. V. van Dokkum
中科院分区：
文献类型：
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作者：
A. Edge;Graham P. Smith;D. Sand;T. Treu;H. Ebeling;S. Allen;P. V. van Dokkum
我们给出了一张哈勃太空望远镜拍摄的星系团A1201(z=0.169)的快照图像，揭示了来自最亮星系团的切线弧线2‘’。凯克·埃切尔光谱仪和成像仪(ESI)光谱证实，弧线本质上是引力的，源星系位于z=0.451。我们建立了一个星团引力势的模型，忠实地再现了观察到的弧形形态。尽管星团在HST框架中呈现出松弛的外观，但总物质分布的最佳椭圆度是ϵ总≥0.5，而卡介苗在2‘’尺度上的光分布(ϵBCG=0.2 3±0.0 3)则相反。还需要对钱德拉进行进一步的深层光学观测和定点X射线光谱成像观测，以确定这种伸长是由于单个拉长的暗物质晕还是由于星系团核心中更复杂的物质分布所致。我们将该弧与从已发表的文献中提取的样本进行了比较，并确认它在所探测的小物理尺度(~6kpc)的切向系统中是唯一的。为了在更广泛的物理尺度上更深入地研究这个星系团，我们使用我们的基准透镜模型估计了半径为6kpc的星系团的投影质量和质光比，得到了M=(5.9)×1011M☉，M/LV=9.4(M/L)☉。总体而言，我们的结果证实了HST快照调查对于识别对星团质量分布的稀有透镜约束的重要性。结合后续的光学和X射线观测，A1201中的弧应有助于增加我们对星系团核心物理的理解。
We present a snapshot Hubble Space Telescope (HST) image of the galaxy cluster A1201 (z = 0.169), revealing a tangential arc 2'' from the brightest cluster galaxy (BCG). Keck Echelle Spectrograph and Imager (ESI) spectroscopy confirms that the arc is gravitational in nature and that the source galaxy lies at z = 0.451. We construct a model of the gravitational potential of the cluster that faithfully reproduces the observed arc morphology. Despite the relaxed appearance of the cluster in the HST frame, the best-fit ellipticity of the total matter distribution is ϵtotal ≥ 0.5, in contrast to the light distribution of the BCG (ϵBCG = 0.23 ± 0.03) on 2'' scales. Further deep optical observations and pointed X-ray spectro-imaging observations with Chandra are required to determine whether this elongation is due to a single elongated dark matter halo or a more complex distribution of matter in the cluster core. We compare the arc with a sample drawn from the published literature and confirm that it is unique among tangential systems in the small physical scales that it probes (~6 kpc). In anticipation of a more thorough investigation of this cluster across a broad range of physical scales, we use our fiducial lens model to estimate the projected mass and mass-to-light ratio of the cluster within a radius of 6 kpc, obtaining M = (5.9) × 1011 M☉, M/LV = 9.4 (M/L)☉. Overall our results confirm the importance of HST snapshot surveys for identifying rare lensing constraints on cluster mass distributions. In combination with follow-up optical and X-ray observations, the arc in A1201 should help to increase our understanding of the physics of cluster cores.