Temporal enhancement of super-horizon curvature perturbations from decays of two curvatons and its cosmological consequences
Temporal enhancement of super-horizon curvature perturbations from decays of two curvatons and its cosmological consequences
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两个曲率衰变引起的超地平线曲率扰动的时间增强及其宇宙学后果
DOI：
10.1103/physrevd.84.083511
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发表时间：
2011
影响因子：
5
通讯作者：
横山順一
中科院分区：
文献类型：
--
作者：
須山輝明;横山順一
如果一个以上的曲率在彼此不同的时期主宰宇宙，曲率扰动可以暂时增强到一个比观测到的值大得多的值。增强的痕迹可以留下高阶相关函数，也就是非高斯性，由标量-标量模耦合产生的随机引力波，以及由增强的曲率扰动的引力崩塌形成的原始黑洞。我们首先通过数值和解析求解线性化的微扰方程，证实了这种时间增强确实发生了。然后，我们导出了全阶曲率微扰的解析表达式，它不依赖于经常使用的突然衰变近似，并且在超视界尺度上是精确的。利用这个解析公式，我们给出了非线性参数、和的表达式。如果两个曲率对最终的曲率扰动都有贡献，那么强的非高斯性出现在三谱而不是双谱中。我们还发现了一个唯一的一致性关系。利用二阶微扰理论，我们数值地证明了诱导引力波的频谱具有与增强持续时间相对应的平台，并且这种引力波可以被UltraDECIGO和空间原子干涉仪探测到。最后，我们计算了原始黑洞的丰度，并对增强的曲率扰动的幅度施加了约束。
If more than one curvaton dominate the Universe at different epochs from each other, curvature perturbations can be temporarily enhanced to a value much larger than the observed one. The traces of the enhancement may be left as higher order correlation functions, that is, as non-Gaussianity, the stochastic gravitational waves that are sourced by scalar-scalar mode couplings, as well as the primordial black holes that are formed by the gravitational collapse of the enhanced curvature perturbations. We first confirm that such a temporal enhancement indeed occurs by solving the linearized perturbation equations both numerically and analytically. We then derive an analytic expression of the full-order curvature perturbation which does not rely on the frequently used sudden decay approximation and is exact on superhorizon scales. By using this analytic formula, we provide expressions of the nonlinearity parameters,and. If both two curvatons contribute to the final curvature perturbations, the strong non-Gaussianity appears in the trispectrum rather than in the bispectrum. We also find a unique consistency relation betweenandwithout. By using the second-order perturbation theory, we numerically show that the spectrum of the induced gravitational waves has a plateau corresponding to duration of the enhancement and such gravitational waves can be probed by ultimate-DECIGO and space-based atomic interferometers. We finally calculate the abundance of the primordial black holes and put a constraint on the amplitude of the enhanced curvature perturbations.
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威尔金森微波各向异性探测器对衰变冷暗物质的约束
DOI：
--
发表时间：
2004
期刊：
Physical Review Letters 93
影响因子：
--
作者：
Ichiki;Oguri;Takahashi
通讯作者：
Takahashi
两个曲线衰减的原始非高斯性
影响因子：
5
作者：
Assadullahi H
通讯作者：
Assadullahi H
影响因子：
--
作者：
R. Saito;J. Yokoyama
通讯作者：
R. Saito;J. Yokoyama
影响因子：
8.7
作者：
Komatsu, E.;Smith, K. M.;Wright, E. L.
通讯作者：
Wright, E. L.
影响因子：
5
作者：
Carr, B. J.;Kohri, Kazunori;Yokoyama, Junichi
通讯作者：
Yokoyama, Junichi