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arXiv 2302.04651astro-ph.CO
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使用折断幂律模型对星系尺度强引力透镜进行质量重建

Mass Reconstruction of Galaxy-scale Strong Gravitational Lenses Using a Broken Power-law Model

Wei Du, Liping Fu, Yiping Shu, Ran Li, Zuhui Fan, Chenggang Shu

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Accepted for publication in ApJ, 24 pages, 13 figures, 2 tables
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AI总结：

本文通过 Illustris-1 模拟图像端到端测试 BPL 模型，证明其在星系尺度强透镜质量、源光重建及速度弥散估计上优于单一幂律模型。

摘要：

利用模拟强引力透镜图像，我们研究了由 \citet{2020ApJ...892...62D} 提出的折断幂律（BPL）模型在星系尺度透镜质量重建中的性能。我们开展了一项端到端测试，包括创建模拟强透镜图像、扣除透镜星系光线以及重建透镜图像，其中透镜样本选自 Illustris-1 模拟中的星系。我们注意到，无论采用何种质量模型（BPL 模型或其特例），仅依靠成像数据即可稳健地确定爱因斯坦半径，其中位偏差通常小于 1%。在远离爱因斯坦半径的位置，透镜质量分布往往更难测量，尤其是在未探测到透镜图像的半径处。我们发现，在严格先验条件下，BPL 模型可明显优于单一幂律模型，在爱因斯坦半径内的径向会聚轮廓上实现小于 5% 的中位偏差。至于源光线重建，我们发现其对透镜光线污染和透镜质量模型均很敏感；在不存在透镜光线污染时，采用严格先验的 BPL 模型仍表现最佳。我们表明，通过校正投影效应，BPL 模型能够以约 6% 的散布精度估计孔径加权和光度加权的视线速度弥散。这些结果凸显了 BPL 模型在强透镜相关研究中的巨大潜力。

英文摘要：

With mock strong gravitational lensing images, we investigate the performance of the broken power-law (BPL) model proposed by \citet{2020ApJ...892...62D} on the mass reconstruction of galaxy-scale lenses. An end-to-end test is carried out, including the creation of mock strong lensing images, the subtraction of lens light, and the reconstruction of lensed images, where the lenses are selected from the galaxies in the Illustris-1 simulation. We notice that, regardless of the adopted mass models (the BPL model or its special cases), the Einstein radius can be robustly determined from imaging data alone, and the median bias is typically less than $1\%$. Away from the Einstein radius, the lens mass distribution tends to be harder to measure, especially at radii where there are no lensed images detected. We find that, with rigid priors, the BPL model can clearly outperform the single power-law models by achieving $<5\%$ median bias on the radial convergence profile within the Einstein radius. As for the source light reconstructions, they are found to be sensitive to both lens light contamination and lens mass models, where the BPL model with rigid priors still performs best when there is no lens light contamination. We show that, by correcting for the projection effect, the BPL model can estimate the aperture and luminosity weighted line-of-sight velocity dispersions to an accuracy of $\sim6\%$ scatter. These results highlight the great potential of the BPL model in strong lensing related studies.

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