Trispectrum of 21-cm background anisotropies as a probe of primordial non-Gaussianity
Trispectrum of 21-cm background anisotropies as a probe of primordial non-Gaussianity
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21 厘米背景各向异性的三谱作为原始非高斯性的探针
DOI：
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发表时间：
2008
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通讯作者：
A. Melchiorri
中科院分区：
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作者：
A. Cooray;Chao Li;A. Melchiorri
再电离时代之前中性氢分布的21厘米各向异性是原始非高斯性的灵敏探针。与宇宙微波背景的情况不同，21厘米的各向异性提供了具有频率选择的多红移信息，并且在弧分角度尺度上不受抑制。我们讨论了21厘米背景各向异性的角三谱，并讨论了如何利用三对一相关器和相应的角功率谱来测量由原始非高斯性产生的三谱信号。我们还讨论了三谱中原始非高斯信息与密度场随后的非线性引力演化所产生的信息的分离。而利用21厘米各向异性的角双谱可以将二阶校正限制在FnL~1以下的原始起伏，利用三谱信息，我们建议三阶耦合项f2或GNL可以被限制在10左右，未来21厘米的观测将在50到100的红移区间内进行。
The 21-cm anisotropies from the neutral hydrogen distribution prior to the era of reionization are a sensitive probe of primordial non-Gaussianity. Unlike the case with cosmic microwave background, 21-cm anisotropies provide multi-redshift information with frequency selection and are not damped at arcminute angular scales. We discuss the angular trispectrum of the 21-cm background anisotropies and discuss how the trispectrum signal generated by the primordial non-Gaussianity can be measured with the three-to-one correlator and the corresponding angular power spectrum. We also discuss the separation of primordial non-Gaussian information in the trispectrum with that generated by the subsequent nonlinear gravitational evolution of the density field. While with the angular bispectrum of 21-cm anisotropies one can limit the second-order corrections to the primordial fluctuations below fNL~1, using the trispectrum information we suggest that the third-order coupling term, f2 or gNL, can be constrained to be around 10 with future 21-cm observations over the redshift interval of 50 to 100.