Towards optimal cosmological parameter recovery from compressed bispectrum statistics
Towards optimal cosmological parameter recovery from compressed bispectrum statistics
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DOI：
10.1093/mnras/stx1681
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发表时间：
2017-05
影响因子：
4.8
通讯作者：
J. Byun;A. Eggemeier;D. Regan;D. Seery;R. Smith
中科院分区：
文献类型：
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作者：
J. Byun;A. Eggemeier;D. Regan;D. Seery;R. Smith
在接下来的十年里，宇宙学参数约束的改进将由宇宙大尺度结构的调查驱动。它们所包含的信息可以通过适当选择的相关函数来测量，并且结构形成的非线性意味着重要的信息将由三点函数或更高的相关函数携带。提取这些信息极具挑战性，需要精确的建模和大量的计算资源来估计描述不同傅立叶配置之间相关性的协方差矩阵。我们调查是否有可能减少这个矩阵，而不显着的信息损失，通过使用代理聚合的双谱的配置的子集。具体地说，我们研究的限制ΛCDM参数从未来的星系调查相结合的功率谱与（a）的积分双谱，（B）的线相关函数和（c）的模式分解的双谱。我们包括一个简单的估计与散粒噪声的双谱的退化。我们的研究结果表明，模态双谱具有可比的性能傅立叶双谱，即使使用比傅立叶配置少得多的模式。线相关函数具有良好的性能，但效果较差。积分双谱对背景宇宙学相对不敏感。与单独的功率谱测量相比，添加双谱数据可以将对偏置参数和σ8的约束改善3到5倍。对于其他参数，最多可提高20%。最后，我们使用一系列的理论模型来探索为每个代理产生现实预测所需的复杂性。
Over the next decade, improvements in cosmological parameter constraints will be driven by surveys of large-scale structure in the Universe. The information they contain can be measured by suitably-chosen correlation functions, and the non-linearity of structure formation implies that significant information will be carried by the three-point function or higher correlators. Extracting this information is extremely challenging, requiring accurate modelling and significant computational resources to estimate the covariance matrix describing correlation between different Fourier configurations. We investigate whether it is possible to reduce this matrix without significant loss of information by using a proxy that aggregates the bispectrum over a subset of configurations. Specifically, we study constraints on ΛCDM parameters from a future galaxy survey combining the power spectrum with (a) the integrated bispectrum, (b) the line correlation function and (c) the modal decomposition of the bispectrum. We include a simple estimate for the degradation of the bispectrum with shot noise. Our results demonstrate that the modal bispectrum has comparable performance to the Fourier bispectrum, even using considerably fewer modes than Fourier configurations. The line correlation function has good performance, but is less effective. The integrated bispectrum is comparatively insensitive to the background cosmology. Addition of bispectrum data can improve constraints on bias parameters and σ8 by a factor between 3 and 5 compared to power spectrum measurements alone. For other parameters, improvements of up to ∼ 20% are possible. Finally, we use a range of theoretical models to explore the sophistication required to produce realistic predictions for each proxy.