Scatter and bias in weak lensing selected clusters
Scatter and bias in weak lensing selected clusters
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DOI：
10.1111/j.1365-2966.2012.21582.x
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发表时间：
2012-04
影响因子：
4.8
通讯作者：
T. Hamana;M. Oguri;M. Shirasaki;Masanori Sato
中科院分区：
文献类型：
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作者：
T. Hamana;M. Oguri;M. Shirasaki;Masanori Sato
我们使用暗物质晕的分析模型和弱透镜星团调查的数值模拟数据来研究弱透镜星团中的散射和偏倚。我们特别关注暗物质在星系团内分布多样性的影响。我们发现，透镜会聚图的峰高与光晕的虚质量相关性很差。对于具有较高平均内部密度（例如M1000）的球形过密度质量，相关性更紧密。研究了光晕形状与峰高的关系，发现光晕多样性引起的均方根散射与峰高呈线性关系，比例因子为0.1 ~ 0.2。发现来自光晕形状的噪声与源星系形状噪声和宇宙剪切噪声相当。我们发现光晕取向偏差显著，即弱透镜选择的星团平均长轴与视距方向一致，并且在高信噪比（S/N）峰值时，取向偏差更强。我们用解析三轴光晕模型计算了取向偏差，得到了与射线追踪结果相当一致的结果。我们开发了一个公式来解析计算弱透镜峰的数目，同时考虑了峰高的所有主要散射源。我们发现改进的分析预测与高信噪比峰值的模拟结果吻合得很好。我们还将预期的数量计数与我们对Subaru/ prime- cam观测的4度2的弱透镜分析结果进行了比较，并发现了很好的一致性。
We examine scatter and bias in weak lensing selected clusters, employing both an analytic model of dark matter haloes and numerical mock data of weak lensing cluster surveys. We pay special attention to effects of the diversity of dark matter distributions within clusters. We find that peak heights of the lensing convergence map correlate rather poorly with the virial mass of haloes. The correlation is tighter for the spherical overdensity mass with a higher mean interior density (e.g. M1000). We examine the dependence of the halo shape on the peak heights, and find that the root mean square scatter caused by the halo diversity scales linearly with the peak heights with the proportionality factor of 0.1–0.2. The noise originated from the halo shape is found to be comparable to the source galaxy shape noise and the cosmic shear noise. We find the significant halo orientation bias, i.e. weak lensing selected clusters on average have their major axes aligned with the line-of-sight direction, and that the orientation bias is stronger for higher signal-to-noise ratio (S/N) peaks. We compute the orientation bias using an analytic triaxial halo model and obtain results quite consistent with the ray-tracing results. We develop a prescription to analytically compute the number count of weak lensing peaks taking into account all the main sources of scatters in the peak heights. We find that the improved analytic predictions agree well with the simulation results for high-S/N peaks of . We also compare the expected number count with our weak lensing analysis results for 4 deg2 of Subaru/Suprime-Cam observations and find a good agreement.