Galaxy bispectrum, primordial non-Gaussianity and redshift space distortions
Galaxy bispectrum, primordial non-Gaussianity and redshift space distortions
复制标题
星系双谱、原初非高斯性和红移空间扭曲
DOI：
10.1088/1475-7516/2016/06/014
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发表时间：
2016
影响因子：
6.4
通讯作者：
Tellarini M
中科院分区：
文献类型：
--
作者：
Tellarini M
对原初密度场的非高斯性的测量有能力大大提高我们对暴胀物理学的理解。事实上，如果我们能将电流测量的精度提高一个数量级，零检测将排除许多类产生原始波动的情况。大规模的星系红移测量代表了有望实现这一目标的实验。因此，我们模拟的星系双谱和预测的准确性，它将探测参数f NL，这代表了原始本地型非高斯的程度。具体来说，我们解决的问题，包括f NL的树级星系双谱的红移空间失真（RSD）建模。我们发现新的贡献与RSD，与本地型非高斯引起的特征大规模放大。这些RSD的影响，必须妥善考虑，以获得无偏的测量F NL从星系双谱。我们提出了一个分析模板，可用于适应大规模的数据，扩展模型中使用的最近的测量。最后，我们进行理想化的预测σ F NL-本地非线性参数F NL的测定精度-从测量的星系双谱。我们的研究结果表明，目前的调查可以在原则上提供f NL的限制与普朗克竞争，未来的调查可以进一步改善他们。
Measurements of the non-Gaussianity of the primordial density field have the power to considerably improve our understanding of the physics of inflation. Indeed, if we can increase the precision of current measurements by an order of magnitude, a null-detection would rule out many classes of scenarios for generating primordial fluctuations. Large-scale galaxy redshift surveys represent experiments that hold the promise to realise this goal. Thus, we model the galaxy bispectrum and forecast the accuracy with which it will probe the parameter f NL, which represents the degree of primordial local-type non Gaussianity. Specifically, we address the problem of modelling redshift space distortions (RSD) in the tree-level galaxy bispectrum including f NL. We find novel contributions associated with RSD, with the characteristic large scale amplification induced by local-type non-Gaussianity. These RSD effects must be properly accounted for in order to obtain un-biased measurements of f NL from the galaxy bispectrum. We propose an analytic template for the monopole which can be used to fit against data on large scales, extending models used in the recent measurements. Finally, we perform idealised forecasts on σ f NL—the accuracy of the determination of local non-linear parameter f NL—from measurements of the galaxy bispectrum. Our findings suggest that current surveys can in principle provide f NL constraints competitive with Planck, and future surveys could improve them further.