arXiv 1903.021192019-03astro-ph.COhep-th

轴子的有效自共振不稳定性

Efficient self-resonance instability from axions

Hayato Fukunaga, Naoya Kitajima, Yuko Urakawa

备注：: 23 pages, 13 figures
发表信息：: JCAP06(2019)055
DOI：: 10.1088/1475-7516/2019/06/055

摘要：

最近的研究表明，轴子的相干振荡可以引起有效的参量共振，导致引力波（GW）的显著发射。在本文中，进行Floquet分析，我们调查的参数共振不稳定性，这可能会触发从轴子的GW的发射。当背景场的时间演化明显偏离谐波振荡时，就会发生这种共振不稳定性。因此，共振不稳定性不能用Mathieu方程描述，其稳定性/不稳定性图是众所周知的。本文通过引入一个可显式计算的参数$\tilde{q}$来区分一般Hill方程所描述的参数共振的不同类型，研究了一般Hill方程的稳定性/不稳定性图。这也可以应用于背景振荡是非谐波的情况。我们发现，扑动共振不稳定性，这发生在$\tilde{q}=O(1)$，通常会导致最显着的增长的非均匀模式之间的自共振不稳定性。我们还研究了在余弦势作用下是否发生扑翼共振。

英文摘要：

It was recently shown that a coherent oscillation of an axion can cause an efficient parametric resonance, leading to a prominent emission of the gravitational waves (GWs). In this paper, conducting the Floquet analysis, we investigate the parametric resonance instability, which potentially triggers the emission of the GWs from axions. Such a resonance instability takes place, when the time evolution of the background field significantly deviates from the harmonic oscillation. Therefore, the resonance instability cannot be described by the Mathieu equation, whose stability/instability chart is well known. In this paper, introducing an explicitly calculable parameter $\tilde{q}$, which can be used to classify different types of the parametric resonance described by the general Hill's equation, we investigate the stability/instability chart for the general Hill's equation. This can also apply to the case where the background oscillation is anharmonic. We show that the flapping resonance instability, which takes place for $\tilde{q}=O(1)$, typically leads to the most significant growth of the inhomogeneous modes among the self-resonance instability. We also investigate whether the flapping resonance takes place for the cosine potential or not.

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英文摘要：

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