The scale-dependent signature of primordial non-Gaussianity in the large-scale structure of cosmic reionization
The scale-dependent signature of primordial non-Gaussianity in the large-scale structure of cosmic reionization
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DOI：
10.1093/mnras/stt926
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发表时间：
2013-04
影响因子：
4.8
通讯作者：
Anson D’Aloisio;Jun Zhang;P. Shapiro;Y. Mao
中科院分区：
文献类型：
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作者：
Anson D’Aloisio;Jun Zhang;P. Shapiro;Y. Mao
宇宙中大尺度结构的兴起取决于暴胀产生的初始密度涨落的统计分布。虽然最简单的通货膨胀模型预测了几乎完美的高斯分布，但更通用的模型预测了与高斯分布的原始偏差，而观察结果可能足够敏感以检测到。普朗克合作组织最近对宇宙微波背景（CMB）温度各向异性双谱的测量显着收紧了对宇宙中原始非高斯性（PNG）水平的观测限制，但它们仍然远离最简单的暴胀模型预测的水平。探测低于 CMB 灵敏度的 PNG 水平将需要其他方法，例如搜索 PNG 在星系晕聚集上的统计印记。在宇宙再电离时期（EoR），第一批恒星和星系将辐射释放到星系际介质（IGM）中，形成电离斑块，其大规模几何形状和演化反映了恒星形成星系的潜在丰度和大规模集群。 IGM 中的电离斑块和银河晕之间的这种统计联系表明，再电离的观测可能提供另一种限制 PNG 的方法。我们采用再电离的线性扰动理论和基于偏移集形式主义的半解析模型来模拟 PNG 对 EoR 的影响。我们通过推导电离密度偏差（即小波数下傅立叶空间中电离原子与总物质超密度之比）来量化 PNG 对再电离大尺度结构的影响。正如之前的研究发现 PNG 在光晕偏差中创建了一个与尺度相关的特征一样，我们也在电离密度偏差中发现了一个与尺度相关的特征。我们的结果与之前文献中描述该 PNG 特征的尝试有很大不同，将应用于其他地方来预测其可观察的后果，例如在21cm的宇宙背景下。
The rise of large-scale structure in the universe depends upon the statistical distribution of initial density fluctuations generated by inflation. While the simplest models of inflation predict an almost perfectly Gaussian distribution, more-general models predict primordial deviations from Gaussianity that observations might yet be sensitive enough to detect. Recent measurements of the Cosmic Microwave Background (CMB) temperature anisotropy bispectrum by the Planck collaboration have significantly tightened observational limits on the level of primordial non-Gaussianity (PNG) in the Universe, but they are still far from the level predicted by the simplest models of inflation. Probing levels of PNG below CMB sensitivities will require other methods, such as searching for the statistical imprint of PNG on the clustering of galactic halos. During the cosmic epoch of reionization (EoR), the first stars and galaxies released radiation into the intergalactic medium (IGM) that created ionized patches whose large-scale geometry and evolution reflected the underlying abundance and large-scale clustering of the star-forming galaxies. This statistical connection between ionized patches in the IGM and galactic halos suggests that observations of reionization may provide another means of constraining PNG. We employ the linear perturbation theory of reionization and semi-analytic models based on the excursion-set formalism to model the effects of PNG on the EoR. We quantify the effects of PNG on the largescale structure of reionization by deriving the ionized density bias, i.e. the ratio of the ionized atomic to total matter overdensities in Fourier space, at small wavenumber. Just as previous studies found that PNG creates a scale-dependent signature in the halo bias, so, too, we find a scale-dependent signature in the ionized density bias. Our results, which differ significantly from previous attempts in the literature to characterize this PNG signature, will be applied elsewhere to predict its observable consequences, e.g. in the cosmic 21cm background.