论文标题
原始非高斯和非高斯协方差
Primordial non-Gaussianity and non-Gaussian Covariance
论文作者
论文摘要
为了追求原始的非高斯，我们希望能够在较大的共同量中获得较小的尺度。在低红移时，对原始非高斯的搜索受到重力崩溃的阻碍，我们经常将其关联到$ k _ {\ rm nl} $。除了这些量表之外，很难重建对原始分布敏感的模式。当预测对原始非高斯性振幅的未来限制时，$ f _ {\ rm nl} $，在协方差中通常会忽略异构成分，因为与对角线相比，它们很小。我们表明，即使所有模式都符合通常被认为是线性状态的，即使所有模式都很好，即使所有模式都很好，因此协方差降低预测的预测限制在协方差降低预测限制中。作为测试地面，我们研究了这些偏高组件对物质Bispectrum对$ f _ {\ rm nl} $的约束能力的影响，这是$ k _ {\ rm max max} $和redshift的函数，并确认了我们对N-Body Simulates to Redshift $ z = 10 $ = 10 $的结果。然后，我们考虑了对氢双光谱的这些影响，如红置$ 2 <z <6 $的PUMA样21厘米强度映射调查所观察到的，并表明不包括非违约的协方差过高预测$ f _ {\ rm nl} $的限制能力，最多可$ 5 $ $ 5 $。对于将来针对更高的红移的未来调查，例如宇宙黎明和黑暗时代，这被认为是原始非高斯的最终调查，我们预计非高斯协方差将严重限制前景，以限制$ f _ {\ rm nl} $从Biseptrum限制。
In the pursuit of primordial non-Gaussianities, we hope to access smaller scales across larger comoving volumes. At low redshift, the search for primordial non-Gaussianities is hindered by gravitational collapse, to which we often associate a scale $k_{\rm NL}$. Beyond these scales, it will be hard to reconstruct the modes sensitive to the primordial distribution. When forecasting future constraints on the amplitude of primordial non-Gaussianity, $f_{\rm NL}$, off-diagonal components are usually neglected in the covariance because these are small compared to the diagonal. We show that the induced non-Gaussian off-diagonal components in the covariance degrade forecast constraints on primordial non-Gaussianity, even when all modes are well within what is usually considered the linear regime. As a testing ground, we examine the effects of these off-diagonal components on the constraining power of the matter bispectrum on $f_{\rm NL}$ as a function of $k_{\rm max}$ and redshift, confirming our results against N-body simulations out to redshift $z=10$. We then consider these effects on the hydrogen bispectrum as observed from a PUMA-like 21-cm intensity mapping survey at redshifts $2<z<6$ and show that not including off-diagonal covariance over-predicts the constraining power on $f_{\rm NL}$ by up to a factor of $5$. For future surveys targeting even higher redshifts, such as Cosmic Dawn and the Dark Ages, which are considered ultimate surveys for primordial non-Gaussianity, we predict that non-Gaussian covariance would severely limit prospects to constrain $f_{\rm NL}$ from the bispectrum.
