arXiv 2006.065942020-06-11astro-ph.CO

利用运动学Sunyaev-Zel'dovich效应和CMB-S4减轻光学深度简并

Mitigating the optical depth degeneracy using the kinematic Sunyaev-Zel'dovich effect with CMB-S4

Marcelo A. Alvarez, Simone Ferraro, J. Colin Hill, Renée Hložek, Margaret Ikape

备注：: 9 pages, 4 figures, comments welcome
发表信息：: Phys. Rev. D 103, 063518 (2021)
DOI：: 10.1103/PhysRevD.103.063518

摘要：

再电离时代是宇宙历史上的主要相变之一，并且是正在进行和即将进行的宇宙微波背景（CMB）实验的焦点，其对小尺度波动的灵敏度有所提高。再电离也代表了一个显着的污染物CMB导出的宇宙学参数约束，由于退化之间的汤姆逊散射光学深度，$τ$，和标量扰动的幅度，$A_s$。这种简并性随后阻碍了大尺度结构数据约束中微子质量总和的能力，这是21世纪20年代宇宙学的主要目标。在这项工作中，我们探讨了运动学Sunyaev-Zel'dovich（kSZ）效应作为再电离的探针，并表明它可以用来减轻光学深度简并与即将到来的CMB-S4实验的高灵敏度，高分辨率的数据。我们讨论了依赖于物理再电离模型参数的kSZ功率谱，以及经验再电离参数，即$τ$和再电离的持续时间，$Δz$。我们表明，通过结合kSZ两点函数和重建的kSZ四点函数，$τ$和$Δz$之间的退化可以被强烈地打破，产生两个参数的严格约束。我们预测的CMB-S4和普朗克数据的组合，包括前景和大气噪声的详细处理的$σ(τ) = 0.003$和$σ(Δz) = 0.25$。对$τ$的约束几乎与从大角度CMB偏振数据获得的宇宙方差极限相同。因此，kSZ效应不仅有望产生关于再电离时期的详细信息，而且还可以对中微子质量进行高精度的宇宙学约束。

英文摘要：

The epoch of reionization is one of the major phase transitions in the history of the universe, and is a focus of ongoing and upcoming cosmic microwave background (CMB) experiments with improved sensitivity to small-scale fluctuations. Reionization also represents a significant contaminant to CMB-derived cosmological parameter constraints, due to the degeneracy between the Thomson-scattering optical depth, $τ$, and the amplitude of scalar perturbations, $A_s$. This degeneracy subsequently hinders the ability of large-scale structure data to constrain the sum of the neutrino masses, a major target for cosmology in the 2020s. In this work, we explore the kinematic Sunyaev-Zel'dovich (kSZ) effect as a probe of reionization, and show that it can be used to mitigate the optical depth degeneracy with high-sensitivity, high-resolution data from the upcoming CMB-S4 experiment. We discuss the dependence of the kSZ power spectrum on physical reionization model parameters, as well as on empirical reionization parameters, namely $τ$ and the duration of reionization, $Δz$. We show that by combining the kSZ two-point function and the reconstructed kSZ four-point function, degeneracies between $τ$ and $Δz$ can be strongly broken, yielding tight constraints on both parameters. We forecast $σ(τ) = 0.003$ and $σ(Δz) = 0.25$ for a combination of CMB-S4 and Planck data, including detailed treatment of foregrounds and atmospheric noise. The constraint on $τ$ is nearly identical to the cosmic-variance limit that can be achieved from large-angle CMB polarization data. The kSZ effect thus promises to yield not only detailed information about the reionization epoch, but also to enable high-precision cosmological constraints on the neutrino mass.

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