纠缠的 $\tau$：普朗克宇宙微波背景对闪光再电离的约束
Tangled $τ$: Planck CMB Constraints on Flash Reionization
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- University of Winnipeg（温尼伯大学）
- University of Manitoba（曼尼托巴大学）
- The University of Tokyo（东京大学）
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中文总结 AI 辅助
本研究首次用MCMC分析闪光再电离模型拟合普朗克CMB数据，发现约束与峰值电离分数紧密相关，且总光学深度无显著变化，PR3数据仅给出上限。
中文摘要 AI 辅助
近期的宇宙学张力重新激发了人们对再电离在参数推断中作用的兴趣，闪光再电离被提出作为一种瞬态的高红移电离事件，它可以在与CMB偏振数据兼容的同时增加汤姆孙光学深度。在本工作中，我们首次对闪光再电离模型进行了马尔可夫链蒙特卡洛分析，并将其拟合到普朗克宇宙微波背景温度、偏振和透镜数据。我们使用普朗克PR4数据在$\Lambda$CDM框架下进行此分析，并包含闪光再电离。我们发现CMB数据允许闪光红移$z_{\rm flash}$有很宽的范围，但约束与峰值电离分数$x_{\rm flash}$紧密相关。对于固定$z_{\rm flash}=20$和$25$的基准闪光再电离场景，我们分别得到约束$x_{\rm flash}=0.24^{+0.13}_{-0.07}$和$x_{\rm flash}=0.15^{+0.07}_{-0.05}$。标准$\Lambda$CDM参数没有表现出显著偏移，特别是再电离的总光学深度没有明显变化，闪光再电离中$\tau=0.061\pm0.007$，而标准tanh参数化中$\tau=0.059\pm0.006$。我们用普朗克PR3数据代替PR4重复此分析，发现对闪光的轻微偏好被95%置信水平的上限所取代，由普朗克PR3数据给出$z_{\rm flash}=20$和$25$时分别有$x_{\rm flash}<0.28$和$x_{\rm flash}<0.18$。
英文摘要
Recent cosmological tensions have renewed interest in the role of reionization in parameter inference, and flash reionization has been proposed as a transient high-redshift ionization episode that can increase the Thomson optical depth while remaining compatible with CMB polarization data. In this work, we present the first Markov Chain Monte Carlo analysis of the flash reionization model fit to Planck cosmic microwave background temperature, polarization, and lensing data. We perform this analysis using Planck PR4 data in $Λ$CDM with flash reionization. We find that CMB data allow a wide range for the redshift of the flash, $z_{\rm flash}$, but with constraints that are tightly correlated with the peak ionization fraction $x_{\rm flash}$. We find constraints $x_{\rm flash}=0.24 ^{+0.13} _{-0.07}$ and $x_{\rm flash}= 0.15 ^{+0.07} _{ - 0.05}$ for the benchmark flash reionization scenarios with fixed $z_{\rm flash}=20$ and $25$ respectively. The standard $Λ$CDM parameters do not exhibit any significant shifts, and in particular, the total optical depth to reionization is not appreciably changed, with $τ=0.061 \pm 0.007$ in flash reionization as compared to $τ=0.059\pm 0.006$ in the standard tanh parametrization. We repeat this analysis for Planck PR3 data in place of PR4, and find that the mild preference for a flash is replaced by 95% CL upper bounds, given by $x_{\rm flash}<0.28$ and $x_{\rm flash}<0.18$ for $z_{\rm flash}=20$ and $25$, respectively, from Planck PR3 data.
