[论文解读] Further support for $S_8$ increasing with effective redshift

Özgür Akarsu, Eoin Ó Colgáin+2 more|arXiv (Cornell University)|Oct 30, 2024

Stochastic processes and financial applications被引用 6

一句话总结

该论文在独立的数据集（Artis et al. 2024 与 Qu et al. 2024）上量化了有效红shift下S8趋势的统计显著性，并将其与早期结果结合，指示约3σ的随红移变化的S8信号。

ABSTRACT

In Adil et al. 2023, we reported an increasing trend in $S_8$ with effective redshift $z_{ extrm{eff}}$ based on $f σ_8(z)$ constraints over the redshift range $0 \lesssim z \lesssim 2$, and predicted that this trend would be observable in independent datasets. Recently, the studies by Artis et al. and the ACT+DESI collaboration appeared, presenting data that aligns with the expected trends. In this letter, we quantify the statistical significance of the increasing $S_8$ trends in recent studies by fitting a linear model to estimate the slope $Δ\,S_8/Δ\, z_{ extrm{eff}}$, and comparing the results to mock simulations. We find probabilities of $p = 0.0163$ and $p = 0.01893$, corresponding to approximately $2.1σ$ for each dataset. Using Fisher's method to combine the independent probabilities, we obtained $p=0.0027$ ($2.8 σ$). When we incorporate our earlier findings, the combined statistical significance reaches between $3σ$ and $3.7σ$. Finally, we discuss how ``scatter" in $σ_8$/$S_8$ constraints from recent DESI full-shape galaxy clustering fits this picture at low statistical significance. This letter continues a series of studies initiated in 2020 that explore redshift-dependent $Λ$CDM parameters as an indication of a breakdown in the standard cosmological model.

研究动机与目标

• Motivate redshift-dependent tests of LambdaCDM parameters to identify potential model breakdowns.
• Quantify the trend of S8 with effective redshift in independent, high-quality datasets.
• Combine results across datasets to assess the overall statistical significance of the trend.
• Discuss implications for cosmology and the robustness of the LambdaCDM framework.

提出的方法

• 对S8与z_eff拟合线性模型，以估计斜率 Delta S8 / Delta z_eff。
• 通过对S8及其误差进行重采样，生成100,000个模拟实现，以计算斜率的原假设分布。
• 从模拟结果为每个数据集计算p值并转换为高斯显著性。
• 使用Fisher方法将独立的p值组合以得到联合显著性。
• 将该趋势与Adil et al. (2023)进行基准比较，并讨论Ω_m演化的含义。

实验结果

研究问题

• RQ1 在独立数据集中，S8 是否随有效红移显著增加？
• RQ2 每个数据集以及联合分析的估计斜率 Delta S8 / Delta z_eff 是多少？
• RQ3 观测到的趋势与Planck-LambdaCDM的预期及潜在系统误差相比如何？
• RQ4 是否存在Ω_m随红shift变化的证据，可能伴随S8趋势？

主要发现

• 对于Artis et al. (2024)数据，斜率为 m = 0.18^{+0.08}_{-0.09}，大约距恒定S8约2σ。
• 对于Qu et al. (2024)数据，斜率为 m = 0.59^{+0.29}_{-0.28}，大约距恒定S8约2.1σ。
• 模拟实现得到Artis et al. (2024)的 p = 0.0163，Qu et al. (2024)的 p = 0.0185，均约为2.1σ显著性。
• Fisher方法将两个独立数据集合并，得到 p = 0.0027（约2.8σ）。
• 将Adil et al. (2023)的结果加入后，总体显著性提升至约3σ至3.7σ之间。
• 综合分析在三组独立数据集中，将随红shift变化的S8趋势大约定位在3σ附近。