SHARP - III. First use of adaptive-optics imaging to constrain cosmology with gravitational lens time delays
SHARP - III. First use of adaptive-optics imaging to constrain cosmology with gravitational lens time delays
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DOI：
10.1093/mnras/stw991
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发表时间：
2016-11-11
影响因子：
4.8
通讯作者：
Vegetti, Simona
中科院分区：
文献类型：
--
作者：
Chen, Geoff C. -F.;Suyu, Sherry H.;Vegetti, Simona
准确和精确地测量哈勃常数对于测试我们目前的标准宇宙学模型和揭示可能的新物理学至关重要。随着哈勃空间望远镜（HST）的成像，每个强引力透镜系统与测量的时间延迟可以允许一个确定的哈勃常数与一个类似的不确定性的7%.Since HST不会永远持续下去，我们探索自适应光学（AO）成像作为一种替代，可以提供更高的角分辨率比HST成像，但由于大气失真有一个不太稳定的点扩散函数（PSF）。为了使AO成像用于时延透镜宇宙学，我们发展了一种方法来提取未知的PSF直接从成像的强透镜类星体。在一个盲测试与两个模拟数据集创建不同的PSF，我们能够恢复重要的宇宙学参数（时间延迟距离，外部剪切，透镜质量剖面斜率，总爱因斯坦半径）。强透镜系统RXJ 1131-1231的Keck Lambda O图像的分析表明，宇宙学的重要参数与基于HST成像和建模的参数在1 σ不确定度内一致。最重要的是，通过使用AO成像与0.09 arcsec分辨率的模型的时间延迟距离的约束是严格的，由类似的50%比通过使用HST成像与0.09 arcsec的时间延迟距离的约束时，采用幂律质量分布的透镜系统。我们的PSF重建技术是通用的，适用于具有多个附近点源的数据集，使需要高精度PSF模型的科学研究成为可能。
Accurate and precise measurements of the Hubble constant are critical for testing our current standard cosmological model and revealing possibly new physics. With Hubble Space Telescope (HST) imaging, each strong gravitational lens system with measured time delays can allow one to determine the Hubble constant with an uncertainty of similar to 7 per cent. Since HST will not last forever, we explore adaptive-optics (AO) imaging as an alternative that can provide higher angular resolution than HST imaging but has a less stable point spread function (PSF) due to atmospheric distortion. To make AO imaging useful for time-delay-lens cosmography, we develop a method to extract the unknown PSF directly from the imaging of strongly lensed quasars. In a blind test with two mock data sets created with different PSFs, we are able to recover the important cosmological parameters (time-delay distance, external shear, lens-mass profile slope, and total Einstein radius). Our analysis of the Keck Lambda O image of the strong lens system RXJ 1131-1231 shows that the important parameters for cosmography agree with those based on HST imaging and modelling within 1 sigma uncertainties. Most importantly, the constraint on the model time-delay distance by using AO imaging with 0.09 arcsec resolution is tighter by similar to 50 per cent than the constraint of time-delay distance by using HST imaging with 0.09 arcsec when a power-law mass distribution for the lens system is adopted. Our PSF reconstruction technique is generic and applicable to data sets that have multiple nearby point sources, enabling scientific studies that require high-precision models of the PSF.