Observational consequences of Bianchi I spacetimes in loop quantum cosmology
Observational consequences of Bianchi I spacetimes in loop quantum cosmology
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DOI：
10.1103/physrevd.102.043523
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发表时间：
2020-06
影响因子：
5
通讯作者：
I. Agulló;J. Olmedo;V. Sreenath
中科院分区：
文献类型：
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作者：
I. Agulló;J. Olmedo;V. Sreenath
各向异性一般支配着均匀宇宙膨胀的最早阶段。它们在弹跳模型中特别重要，因为剪切在宇宙的收缩阶段增长，使各向同性的情况不稳定。本文将圈量子宇宙学（LQC）中的宇宙学微扰研究扩展到各向异性的比安奇I模型，该模型包含一个反弹，随后是一个慢卷暴胀阶段。我们表明，虽然剪切张量稀释和宇宙各向同性反弹后不久，宇宙扰动保持记忆的这个短的各向异性阶段。我们开发了描述各向异性，有效LQC中的扰动所需的形式主义，并将其应用于宇宙微波背景（CMB）的预测，同时尊重当前的观测约束。我们表明，各向异性反弹诱导：（i）在CMB中的所有角相关函数的各向异性功能，特别是四极调制，可以解释普朗克卫星在温度图中观察到的类似功能，和（ii）标量和张量模式之间的量子纠缠，表现在CMB中的温度-偏振（T-B和E-B）相关。
Anisotropies generically dominate the earliest stages of expansion of a homogeneous universe. They are particularly relevant in bouncing models, since shears grow in the contracting phase of the cosmos, making the isotropic situation unstable. This paper extends the study of cosmological perturbations in loop quantum cosmology (LQC) to anisotropic Bianchi I models that contain a bounce followed by a phase of slow-roll inflation. We show that, although the shear tensor dilutes and the universe isotropizes soon after the bounce, cosmic perturbations retain memory of this short anisotropic phase. We develop the formalism needed to describe perturbations in anisotropic, effective LQC, and apply it to make predictions for the cosmic microwave background (CMB), while respecting current observational constraints. We show that the anisotropic bounce induces: (i) anisotropic features in all angular correlation functions in the CMB, and in particular a quadrupolar modulation that can account for a similar feature observed in the temperature map by the Planck satellite, and (ii) quantum entanglement between scalar and tensor modes, that manifests itself in temperature-polarization (T-B and E-B) correlations in the CMB.