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arXiv 1405.2020astro-ph.CO
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张量的广义慢滚

Generalized Slow Roll for Tensors

Wayne Hu

摘要:

最近BICEP 2检测度尺度CMB B模式偏振,再加上大角度温度各向异性的观测功率不足,表明慢滚参数$ε_H$,哈勃速率每倍的分数变化,都是相对较大的,并可能从一个更大的值在尺度上大于重组时的视界。相对较大的张量的贡献也意味着需要有限的匹配功能,在张量功率谱的任何标量功率谱功能提出解释温度数据中的异常。我们扩展了广义慢卷的方法计算功率谱,适合于这种模型的慢卷参数变化,标量功能是大的张量功能。这种方法还将张量-标量一致性关系推广到张量源和标量源的比率与两个功率谱中的特征之间。张量谱中的特征通常被相对于标量谱中的特征的$ε_H$和哈勃速率的平滑性所抑制,哈勃速率必须服从协变的能量守恒,而不是其导数。在不久的将来CMB数据中检测到它们将表明膨胀的快速滚动期,其中$ε_H$接近阶数单位,这是温度异常的膨胀解释所允许但不要求的。

英文摘要:

The recent BICEP2 detection of degree scale CMB B-mode polarization, coupled with a deficit of observed power in large angle temperature anisotropy, suggest that the slow-roll parameter $ε_H$, the fractional variation in the Hubble rate per efold, is both relatively large and may evolve from an even larger value on scales greater than the horizon at recombination. The relatively large tensor contribution implied also requires finite matching features in the tensor power spectrum for any scalar power spectrum feature proposed to explain anomalies in the temperature data. We extend the generalized slow-roll approach for computing power spectra, appropriate for such models where the slow-roll parameters vary, to tensor features where scalar features are large. This approach also generalizes the tensor-scalar consistency relation to be between the ratio of tensor and scalar sources and features in the two power spectra. Features in the tensor spectrum are generically suppressed by $ε_H$ relative those in the scalar spectrum and by the smoothness of the Hubble rate, which must obey covariant conservation of energy, versus its derivatives. Their detection in near future CMB data would indicate a fast roll period of inflation where $ε_H$ approaches order unity, allowed but not required by inflationary explanations of temperature anomalies.

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