Primordial tensor bispectra in μ-CMB cross-correlations
Primordial tensor bispectra in μ-CMB cross-correlations
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DOI：
10.1088/1475-7516/2022/02/004
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发表时间：
2021-09
影响因子：
6.4
通讯作者：
Giorgio Orlando;P. Meerburg;S. Patil
中科院分区：
文献类型：
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作者：
Giorgio Orlando;P. Meerburg;S. Patil
宇宙微波背景（CMB）温度与偏振各向异性和μ谱畸变之间的相互关系被认为可以测量（压缩）原初标量双谱，其尺度范围是原初微波背景双谱无法达到的。在这项工作中，我们讨论了是否有可能用这些相互关联来约束张量的非高斯性。我们发现只有具有统计各向异性的原始张量双谱会留下明显的特征，而各向同性张量双谱会留下消失或高度抑制的特征。我们讨论了压缩双谱在短动量和长动量方面的角依赖性如何决定非零相互关系。我们还讨论了原始双谱在宇称下变换的方式对这些非消失构型的影响。通过采用所谓的BipoSH形式来捕捉统计各向异性的观测效应，我们通过μ T， μ E和μ B互相关进行fisher预测来评估探测前景。在⟨γγγ⟩和⟨γγζ⟩的压缩双谱中观察统计各向异性将是具有挑战性的，因为μ-畸变上的张量扰动的印记是次占主导地位的标量扰动，因此需要在μ-epoch中对张量扰动的影响进行大的，独立的放大。在没有这种机制的情况下，⟨ζζγ⟩压缩双谱中的统计各向异性是μ T， μ E和μ B相互关联的最相关来源。特别地，我们指出在⟨ζζ⟩在μ T和μ E中留下潜在可观察签名的各向异性暴胀模型中，源自μ B的⟨ζ γ⟩的检测前景得到增强。
Cross-correlations between Cosmic Microwave Background (CMB) temperature and polarization anisotropies and μ-spectral distortions have been considered to measure (squeezed) primordial scalar bispectra in a range of scales inaccessible to primary CMB bispectra. In this work we address whether it is possible to constrain tensor non-Gaussianities with these cross-correlations. We find that only primordial tensor bispectra with statistical anisotropies leave distinct signatures, while isotropic tensor bispectra leave either vanishing or highly suppressed signatures. We discuss how the angular dependence of squeezed bispectra in terms of the short and long momenta determine the non-zero cross-correlations. We also discuss how these non-vanishing configurations are affected by the way in which primordial bispectra transform under parity. By employing the so-called BipoSH formalism to capture the observational effects of statistical anisotropies, we make Fisher-forecasts to assess the detection prospects from μ T, μ E and μ B cross-correlations. Observing statistical anisotropies in squeezed ⟨γγγ⟩ and ⟨γγζ⟩ bispectra is going to be challenging as the imprint of tensor perturbations on μ-distortions is subdominant to scalar perturbations, therefore requiring a large, independent amplification of the effect of tensor perturbations in the μ-epoch. In absence of such a mechanism, statistical anisotropies in squeezed ⟨ζζγ⟩ bispectrum are the most relevant sources of μ T, μ E and μ B cross-correlations. In particular, we point out that in anisotropic inflationary models where ⟨ζζζ⟩ leaves potentially observable signatures in μ T and μ E, the detection prospects of ⟨ζζγ⟩ from μ B are enhanced.