Identifying Lensed Quasars and Measuring Their Time Delays from Unresolved Light Curves
Identifying Lensed Quasars and Measuring Their Time Delays from Unresolved Light Curves
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DOI：
10.3847/1538-4357/ac51cb
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发表时间：
2021-10
期刊：
影响因子：
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通讯作者：
S. Bag;A. Shafieloo;Kai Liao;T. Treu
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文献类型：
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作者：
S. Bag;A. Shafieloo;Kai Liao;T. Treu
识别多幅成像的类星体具有挑战性，因为它们在天空中的密度很低，而且广域调查的角度分辨率有限。我们证明，多重成像类星体可以使用未分辨的光曲线来识别，而不需要假设光曲线模板或任何先验信息。在描述了我们的方法之后，我们用仿真表明，当我们考虑高质量的数据时，它可以达到高精度和召回率，而噪声可以忽略不计，远远低于光曲线的变化性。随着噪声水平增加到兹维基瞬变设施望远镜的水平，我们发现准确率可以保持接近100%，而召回率下降到∼的60%。我们还考虑了时延挑战1中的一些例子，并证明了在实际观测场景中，可以从联合光曲线数据中准确地恢复时延。我们进一步演示了我们的方法，将它应用于可公开获得的观测透镜类星体SDSSJ1226−0006的COSMOGRAIL数据。我们根据未分辨的光曲线将该系统识别为透镜类星体，并利用单独的图像光曲线估计了与COSMOGRAIL测量的时间延迟很好一致的时间延迟。这项技术显示出在广域成像测量中识别透镜类星体的巨大潜力，特别是即将投入使用的维拉鲁宾天文台。
Identifying multiply imaged quasars is challenging owing to their low density in the sky and the limited angular resolution of wide-field surveys. We show that multiply imaged quasars can be identified using unresolved light curves, without assuming a light-curve template or any prior information. After describing our method, we show, using simulations, that it can attain high precision and recall when we consider high-quality data with negligible noise well below the variability of the light curves. As the noise level increases to that of the Zwicky Transient Facility telescope, we find that precision can remain close to 100% while recall drops to ∼60%. We also consider some examples from Time Delay Challenge 1 and demonstrate that the time delays can be accurately recovered from the joint light-curve data in realistic observational scenarios. We further demonstrate our method by applying it to publicly available COSMOGRAIL data of the observed lensed quasar SDSS J1226−0006. We identify the system as a lensed quasar based on the unresolved light curve and estimate a time delay in good agreement with the one measured by COSMOGRAIL using the individual image light curves. The technique shows great potential to identify lensed quasars in wide-field imaging surveys, especially the soon-to-be-commissioned Vera Rubin Observatory.