Reionization and cosmic microwave background distortions: A complete treatment of second-order Compton scattering.
Reionization and cosmic microwave background distortions: A complete treatment of second-order Compton scattering.
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再电离和宇宙微波背景畸变：二阶康普顿散射的完整处理。
DOI：
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发表时间：
1993
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通讯作者：
Douglas ScottJoseph Silk
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作者：
Wayne Hu;Douglas ScottJoseph Silk
宇宙的电离历史为使用小角尺度微波背景各向异性约束宇宙学模型提供了模糊性的主要来源。为了澄清这些问题，我们考虑将康普顿散射完全处理为二阶，这种方法可能适用于其他天体物理情况。我们发现只有 ${cal O} (v)$ 多普勒效应和 ${cal O} (vdelta)$ Vishniac 效应对于最近的最后一个散射历元很重要； ${cal O} (v^2)$ 多普勒效应在任何角度尺度上都不显着，其他高阶效应完全可以忽略不计。然而，${cal O}(v^2)$ 效应确实会导致 Cy 畸变，虽然通常低于当前限制，但在再电离模型中设置了不可避免的最低水平。我们详细考虑了 Vishniac 效应的小角度近似，并展示了比以前的处理方法的一些改进，特别是对于低 $Omega_0$。对于标准冷暗物质模型，再电离的作用是将各向异性重新分布到弧分尺度；晚期再电离导致部分消除了初级波动和相当幅度的次级贡献。利用 ATCA 实验的最新各向异性限制，我们对重子暗物质模型设置了新的约束。对具有更高哈勃常数、更陡峭的 $n$ 和更高密度的模型施加更强的约束（按二阶）。这些限制取决于假设的特定电离历史，但通过降低电离分数获得的因子通常很小，并且可以通过当前计划的测试
The ionization history of the universe provides a major source of ambiguity in constraining cosmological models using small angular scale microwave background anisotropies. To clarify these issues, we consider a complete treatment of Compton scattering to second order, an approach which may be applicable to other astrophysical situations. We find that only the ${cal O} (v)$ Doppler effect, and the ${cal O} (vdelta)$ Vishniac effect are important for recent last scattering epochs; the ${cal O} (v^2)$ Doppler effect is not significant on any angular scale, and other higher-order effects are completely negligible. However the ${cal O}(v^2)$ effect does lead to Cy distortions, which although generally below current constraints, set an unavoidable minimum level in reionization models. We consider the small-angle approximation for the Vishniac effect in detail, and show several improvements over previous treatments, particularly for low $Omega_0$. For standard cold dark matter models, the effect of reionization is to redistribute the anisotropies to arcminute scales; late reionization leads to partially erased primary fluctuations and a secondary contribution of comparable magnitude. Using recent anisotropy limits from the ATCA experiment, we set new constraints on baryonic dark matter models. Stronger constraints are imposed (in second order) upon models with higher Hubble constant, steeper $n$, and higher density. These limits depend on the specific ionization history assumed, but the factor gained by lowering the ionization fraction is generally small, and may be tested by currently-planned