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arXiv 2112.01409astro-ph.COhep-ph
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相变引力波的各向异性及其对宇宙原始种子的意义

Anisotropy of phase transition gravitational wave and its implication for primordial seeds of the Universe

Yongping Li, Fa Peng Huang, Xiao Wang, Xinmin Zhang

摘要:

我们定量地研究了原初密度涨落如何影响相变引力波(PTGW)的各向异性。各向异性的PTGW在重组之前很久就产生了,并且没有丝绸阻尼,它可能揭示了由暴胀或替代品引起的密度扰动。我们发现PTGW各向异性功率谱的新行为。PTGW各向异性在所有尺度上都强于宇宙微波背景温度的各向异性,早期积分的Sachs-Wolfe效应使高$\ell$多次波增强约1个数量级。此外,原始功率谱在小尺度上的差异表现出更显着的PTGW各向异性的角功率谱相比,宇宙微波背景。这些性质可能为理解我们早期宇宙的原始密度扰动提供新的线索,从而完善我们对暴胀理论的理解。以暗物质模型中的纳赫兹PTGW为例,我们得到了PTGW各向异性的振幅,比各向同性的PTGW能谱弱4 ~ 3个数量级。

英文摘要:

We quantitatively study how the primordial density fluctuations are imprinted on the anisotropy of the phase transition gravitational wave (PTGW). Generated long before recombination and free from Silk damping, the anisotropic PTGW might reveal the density perturbation seeded from inflation or alternatives. We find new behaviors of the PTGW anisotropy power spectrum. The PTGW anisotropy is stronger than the anisotropy of the cosmic microwave background temperature at all scales, and the high-$\ell$ multiples are enhanced about 1 order due to the early integrated Sachs-Wolfe effect. Furthermore, differences in primordial power spectra at small scales manifest themselves more significantly on the angular power spectrum of PTGW anisotropy compared to that of the cosmic microwave background. These properties might provide a novel clue to understanding the primordial density perturbation of our early Universe and thereby complete our understanding of inflation theory. Taking nanohertz PTGW from dark matter models as a typical example, we obtain amplitudes of PTGW anisotropy which are about 4 or 3 orders weaker than the isotropic PTGW energy spectra.

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