Observations and Theoretical Implications of the Large-Separation Lensed Quasar SDSS J1004+4112
Observations and Theoretical Implications of the Large-Separation Lensed Quasar SDSS J1004+4112
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DOI：
10.1086/382221
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发表时间：
2003-12
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通讯作者：
M. Oguri;N. Inada;C. Keeton;B. Pindor;J. Hennawi;M. D. Gregg;Robert H. Becker;K. Chiu;Wei Zheng;S. Ichikawa;Yasushi Suto;Edwin L. Turner;J. Annis;N. Bahcall;J. Brinkmann;F. Castander;D. Eisenstein;J. Frieman;Tomotsugu Goto;J. Gunn;D. Johnston;Stephen M. Kent;R. Nichol;G. T. Richards;H. Rix;D. Schneider;E. Sheldon;A. Szalay
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作者：
M. Oguri;N. Inada;C. Keeton;B. Pindor;J. Hennawi;M. D. Gregg;Robert H. Becker;K. Chiu;Wei Zheng;S. Ichikawa;Yasushi Suto;Edwin L. Turner;J. Annis;N. Bahcall;J. Brinkmann;F. Castander;D. Eisenstein;J. Frieman;Tomotsugu Goto;J. Gunn;D. Johnston;Stephen M. Kent;R. Nichol;G. T. Richards;H. Rix;D. Schneider;E. Sheldon;A. Szalay
我们研究了最近发现的引力透镜 SDSS J1004+4112，这是第一个被星系团透镜化的类星体。它由四张图像组成，最大间隔为 14.″62。该系统选自斯隆数字巡天（SDSS）的光度数据，并在深度成像和光谱后续观测的基础上被确认为z = 1.734的透镜类星体。我们提出了透镜附近星系的颜色-星等关系以及三个中心星团成员的光谱，这明确地证实了 z = 0.68 处的星团是造成大图像分离的原因。我们发现了与数据一致的各种透镜模型，尽管存在相当大的多样性，但它们提出了四个一般性结论：（1）最亮的星团星系和星团势阱的中心似乎偏移了几千秒差距； （2）星团质量分布必须在南北方向拉长，这与观测到的星团星系分布一致； (3) 大潮汐切变 (~0.2) 的推断表明星团中有重要的子结构； (4) 图像之间的预测时间延迟存在巨大的不确定性，这意味着测量延迟将极大地改善对模型的约束。我们还根据冷暗物质模型计算了 SDSS 类星体样本中出现这种大分离透镜效应的概率。之前的调查中缺乏大分离透镜，并且在 SDSS 中发现了大分离透镜，这意味着如果团簇暗物质晕具有内部密度分布 ρ ∝ r-1.5，则质量涨落归一化 σ8 = 1.0（95% 置信度）。轮廓越浅则需要更高的 σ8 值。尽管统计结论可能在一定程度上取决于透镜势的复杂程度，但SDSS J1004+4112的发现与冷暗物质场景中星团尺度晕丰度的预测是一致的。
We study the recently discovered gravitational lens SDSS J1004+4112, the first quasar lensed by a cluster of galaxies. It consists of four images with a maximum separation of 14.″62. The system was selected from the photometric data of the Sloan Digital Sky Survey (SDSS) and has been confirmed as a lensed quasar at z = 1.734 on the basis of deep imaging and spectroscopic follow-up observations. We present color-magnitude relations for galaxies near the lens plus spectroscopy of three central cluster members, which unambiguously confirm that a cluster at z = 0.68 is responsible for the large image separation. We find a wide range of lens models consistent with the data, and despite considerable diversity they suggest four general conclusions: (1) the brightest cluster galaxy and the center of the cluster potential well appear to be offset by several kiloparsecs; (2) the cluster mass distribution must be elongated in the north-south direction, which is consistent with the observed distribution of cluster galaxies; (3) the inference of a large tidal shear (~0.2) suggests significant substructure in the cluster; and (4) enormous uncertainty in the predicted time delays between the images means that measuring the delays would greatly improve constraints on the models. We also compute the probability of such large-separation lensing in the SDSS quasar sample on the basis of the cold dark matter model. The lack of large-separation lenses in previous surveys and the discovery of one in SDSS together imply a mass fluctuation normalization σ8 = 1.0 (95% confidence) if cluster dark matter halos have an inner density profile ρ ∝ r-1.5. Shallower profiles would require higher values of σ8. Although the statistical conclusion might be somewhat dependent on the degree of the complexity of the lens potential, the discovery of SDSS J1004+4112 is consistent with the predictions of the abundance of cluster-scale halos in the cold dark matter scenario.