AI 中文总结
该研究针对ΛCDM模型下BAO与CMB数据的差异，探究高红移原初黑洞蒸发产生的额外光学深度能否缓解差异，发现其提升量不足，无法显著消除差异。
AI 中文摘要
在ΛCDM模型框架下分析时，重子声学振荡（BAO）和宇宙微波背景（CMB）数据存在一定差异，表现为“物质密度缺失”和“CMB透镜过度”两种现象。一种可能的解决思路是增加复合后宇宙中自由电子的散射光学深度τ，这一可能性由Sailer等人（2025）和Jhaveri等人（2025）提出。由于普朗克卫星对低阶偏振“再电离峰”的测量已从标准恒星驱动的再电离过程（红移z<10）中约束了τ值，我们研究高红移处奇异过程导致的瞬时或部分再电离所产生的额外光学深度。为明确起见，我们探究了单谱原初黑洞（PBH）的霍金辐射的影响，同时保留了约束这类演化过程的高阶TT/TE/EE数据，并联合改变再电离红移。我们发现CMB数据并未显著偏好这些额外信号：最大提升量为Δτ≈0.008，远小于完全消除中等差异所需的Δτ≈0.03；物质密度缺失和透镜过度也未得到显著缓解，我们对此进行了解释，指出这源于再电离红移与ℓ>30处剩余PBH信号的补偿效应。
英文摘要
BAO and CMB data are somewhat discrepant when interpreted in the context of $Λ$cdm, discrepancies that show up as a `matter density deficit' and as a `CMB lensing excess'. One possible resolution is an increased optical depth to scattering off of free electrons in the post-recombination universe, $τ$, a possibility raised by Sailer et al. 2025 and Jhaveri et al. 2025. Since Planck measurements of the low-$\ell$ polarization `reionization bump' already constrain $τ$ from standard stellar-driven reionization at $z<10$, we investigate additional optical depth sourced by transient or partial reionization at higher redshift from exotic processes. For specificity, we explore the impact of Hawking radiation from a monochromatic spectrum of primordial black holes, retaining the high-$\ell$ $TT/TE/EE$ data that constrain such histories and varying the reionization redshift jointly. We find that the CMB data do not significantly prefer these additional signals: the boost is at most $Δτ\simeq 0.008$, well short of the $Δτ\simeq 0.03$ that would completely eliminate the moderate discrepancy. The matter density deficit and the lensing excess are not significantly eased: we explain why, tracing it to compensation from the reionization redshift and the residual PBH signal at $\ell > 30$.
Comments17 pages, 6 figures. Comments welcome
