Chitah: STRONG-GRAVITATIONAL-LENS HUNTER IN IMAGING SURVEYS
Chitah: STRONG-GRAVITATIONAL-LENS HUNTER IN IMAGING SURVEYS
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DOI：
10.1088/0004-637x/807/2/138
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发表时间：
2014-11
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影响因子：
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通讯作者：
J. Chan;S. Suyu;T. Chiueh;A. More;P. Marshall;J. Coupon;M. Oguri;P. Price
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文献类型：
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作者：
J. Chan;S. Suyu;T. Chiueh;A. More;P. Marshall;J. Coupon;M. Oguri;P. Price
强引力透镜类星体为研究星系演化和宇宙学提供了强有力的手段。目前和即将进行的成像调查将包含数千个新的透镜类星体，将现有样本增加至少两个数量级。为了找到这样的透镜系统，我们建造了一个机器人Chitah，它通过对多个类星体图像的配置进行建模来寻找透镜类星体。具体地说，给定一个可能是透镜类星体的物体的图像，Chitah首先根据颜色信息分离来自假想的透镜星系的光和来自多个类星体图像的光。设计了一条简单的规则来将给定的物体归类为潜在的四像(四像)或两像(双)透镜类星体系统。随后对所识别的类星体图像的配置进行建模以分类该对象是否是透镜类星体系统。我们使用基于加拿大-法国-夏威夷望远镜遗产调查的模拟透镜系统来测试Chitah的性能。对于用高斯点扩散函数模拟的具有大像距(爱因斯坦半径为11)的明亮四边形，∼的高真阳性率为90%，低的假阳性率∼为3%，这表明这是一种很有前途的寻找新透镜系统的方法。对于≳为0.5的透镜系统，我们获得了很高的TPR值，因此，它的性能是由视力决定的。我们进一步将一个已知的引力透镜系统宇宙5921+0638馈送给Chitah，并证明了Chitah能够成功地对这个真实的引力透镜系统进行分类。我们新建造的吉塔是杂食性的，可以在任何地面成像测量中捕猎。
Strong gravitationally lensed quasars provide powerful means to study galaxy evolution and cosmology. Current and upcoming imaging surveys will contain thousands of new lensed quasars, augmenting the existing sample by at least two orders of magnitude. To find such lens systems, we built a robot, Chitah, that hunts for lensed quasars by modeling the configuration of the multiple quasar images. Specifically, given an image of an object that might be a lensed quasar, Chitah first disentangles the light from the supposed lens galaxy and the light from the multiple quasar images based on color information. A simple rule is designed to categorize the given object as a potential four-image (quad) or two-image (double) lensed quasar system. The configuration of the identified quasar images is subsequently modeled to classify whether the object is a lensed quasar system. We test the performance of Chitah using simulated lens systems based on the Canada–France–Hawaii Telescope Legacy Survey. For bright quads with large image separations (with Einstein radius r ein > 1 1 ?> ) simulated using Gaussian point-spread functions, a high true-positive rate (TPR) of ∼ 90 % ?> and a low false-positive rate of ∼ 3 % ?> show that this is a promising approach to search for new lens systems. We obtain high TPR for lens systems with r ein ≳ 0 5 ?> , so the performance of Chitah is set by the seeing. We further feed a known gravitational lens system, COSMOS 5921+0638, to Chitah, and demonstrate that Chitah is able to classify this real gravitational lens system successfully. Our newly built Chitah is omnivorous and can hunt in any ground-based imaging surveys.