SDSS J2222+2745: A GRAVITATIONALLY LENSED SEXTUPLE QUASAR WITH A MAXIMUM IMAGE SEPARATION OF 15.″1 DISCOVERED IN THE SLOAN GIANT ARCS SURVEY
SDSS J2222+2745: A GRAVITATIONALLY LENSED SEXTUPLE QUASAR WITH A MAXIMUM IMAGE SEPARATION OF 15.″1 DISCOVERED IN THE SLOAN GIANT ARCS SURVEY
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SDSS J2222+2745：斯隆巨弧调查中发现的最大图像间隔为 15.″1 的引力透镜六类星体
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发表时间：
2012
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通讯作者：
J. Fynbo
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作者：
H. Dahle;M. Gladders;K. Sharon;M. Bayliss;E. Wuyts;L. Abramson;Benjamin P. Koester;N. Groeneboom;T. E. Brinckmann;M. T. Kristensen;M. Lindholmer;A. Nielsen;J. Krogager;J. Fynbo
我们报告发现了一个独特的引力透镜系统，SDSS J2222+2745，产生五个光谱证实的图像zs = 2.82类星体透镜的前景星系团在zl = 0.49。我们还提出了光度和光谱证据的第六透镜图像相同的类星体。类星体图像之间的最大间隔为15.“1。在已知的透镜类星体中，大的图像分离和高的图像多重性本身都是罕见的，在目前的数据集中，观察这两个因素的组合是非常不可能发生的。这是已知的第三个类星体被星团透镜化的例子，也是唯一一个有六张图像的例子。透镜系统是在斯隆巨弧巡天过程中发现的，我们在斯隆数字巡天中确定了候选透镜，并用2.56米北欧光学望远镜对这些透镜进行了跟踪和验证。从2011年9月到2012年9月，在多个时期获得的多波段测光显示，在一些类星体图像中存在10%-30%的显著变化，这表明测量类星体图像之间的相对时间延迟是可行的。在这个透镜系统中，我们还确定了一个明亮的（g = 21.5）巨大的弧对应于一个强透镜背景星系在zs = 2.30。我们拟合的透镜系统的参数模型，约束的红移和位置的类星体图像和红移和位置的巨大的弧。不同对类星体图像之间的预测时间延迟范围从100天到106年。
We report the discovery of a unique gravitational lens system, SDSS J2222+2745, producing five spectroscopically confirmed images of a zs = 2.82 quasar lensed by a foreground galaxy cluster at zl = 0.49. We also present photometric and spectroscopic evidence for a sixth lensed image of the same quasar. The maximum separation between the quasar images is 15.″1. Both the large image separations and the high image multiplicity are in themselves rare among known lensed quasars, and observing the combination of these two factors is an exceptionally unlikely occurrence in present data sets. This is only the third known case of a quasar lensed by a cluster, and the only one with six images. The lens system was discovered in the course of the Sloan Giant Arcs Survey, in which we identify candidate lenses in the Sloan Digital Sky Survey and target these for follow-up and verification with the 2.56 m Nordic Optical Telescope. Multi-band photometry obtained over multiple epochs from 2011 September to 2012 September reveals significant variability at the ∼10%–30% level in some of the quasar images, indicating that measurements of the relative time delay between quasar images will be feasible. In this lens system, we also identify a bright (g = 21.5) giant arc corresponding to a strongly lensed background galaxy at zs = 2.30. We fit parametric models of the lens system, constrained by the redshift and positions of the quasar images and the redshift and position of the giant arc. The predicted time delays between different pairs of quasar images range from ∼100 days to ∼6 yr.