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arXiv 2409.13404astro-ph.CO
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利用第三阶段弱引力透镜巡天重建物质功率谱的第一步

First step toward matter power spectrum reconstruction with Stage III weak gravitational lensing surveys

Jeger C. Broxterman, Konrad Kuijken

AI总结:

本文提出用双幂律参数模型从第三阶段弱引力透镜巡天数据直接重建物质功率谱,以定位 $S_8$ tension 来源,但发现当前约束仍较弱。

摘要:

弱引力透镜(WL)巡天为广泛尺度范围内的物质分布提供了洞察。当前的 WL 结果与来自早期宇宙的宇宙微波背景测量存在轻度 tension。从其测量中重建物质功率谱,而不是将信息压缩为单一宇宙学参数,可能有助于定位这些差异的来源。为研究第三阶段 WL 巡天的宇宙剪切测量,我们通过假设一个简单的物质功率谱参数模型来比较它们的层析数据。该模型允许比较具有不同特征的巡天,并以一种不可知论的方法揭示数据所偏好的物质功率谱形状。对于物质功率谱,我们假设在尺度因子和波数上采用双幂律模型。最佳拟合幅度和指数通过 MCMC 分析推断。我们确定了数据最敏感的尺度。我们测试了对不同内禀对齐强度假设的敏感性。我们发现第三阶段巡天对功率谱形状和演化的约束能力仍然有限。大部分信息可以概括为在波数和尺度因子的一个枢轴点处的总体幅度,而对幂律指数的约束则明显较弱。尽管如此,所有巡天都显示出从 $z=$ 0.5 到 0.1 的增长速率比预测更弱。发现所假设的内禀对齐强度对测量参数和拟合优度没有显著影响。原则上,来自第三阶段弱透镜巡天的物质功率谱直接估计可用于定位观测到的 $S_8$ tension 的物理起源。我们为朝这一方向迈出的第一步提出了一种简单的方法,但发现当前的约束仍然较弱。

英文摘要:

Weak gravitational lensing (WL) surveys provide insight into the matter distribution over an extensive range of scales. Current WL results are in mild tension with cosmic microwave background measurements from the early Universe. Reconstructing the matter power spectrum from their measurements instead of condensing the information into a single cosmological parameter may help locate the origin of these differences. To investigate the cosmic shear measurements of Stage III WL surveys, we compared their tomographic data by assuming a simple parametric model for the matter power spectrum. The model allows the comparison of surveys with different characteristics and, in an agnostic approach, gives insight into the shape of the matter power spectrum preferred by the data. For the matter power spectrum, we assumed a double power-law model in scale factor and wavenumber. The best-fitting amplitude and exponents were inferred in an MCMC analysis. We identified the scales to which the data is most sensitive. We tested the sensitivity to different assumptions of the intrinsic alignment strength. We find that the constraining power of Stage III surveys on the power spectrum shape and evolution is still limited. Most information can be summarized as an overall amplitude at a pivot point in wavenumber and scale factor, while constraints on the power-law indices are considerably weaker. Nevertheless, all surveys show a weaker rate of growth from $z=$ 0.5 to 0.1 than predicted. The assumed intrinsic alignment strength is found to have no significant impact on the measured parameters and goodness of fit. Direct estimates of the matter power spectrum from Stage III weak lensing surveys can, in principle, be used to locate the physical origin of the observed $S_8$ tension. We present a simple methodology for the first steps in this direction, but find that current constraints are still weak.

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