Gravitational wave production from axion dark matter in the early universe

轴子和轴子类粒子(Alp)既是强CP问题的解，也是暗物质的候选者。最近，我们已经证明，在早期宇宙中由轴子动力学产生的引力波可能会在未来的引力波实验中被探测到。这是可能的，如果轴子耦合到一个暗光子，然后在轴子朝着其势的原点滚动时，暗光子经历了一个速子不稳定性。这一提议的目的是通过以下方式进一步探索这种可能性：i)确定可以使用引力波探测的轴子参数空间的区域；ii)对产生机制进行更精确的数值模拟；iii)开发将轴子信号与其他引力波源区分开来的方法；以及iv)将其应用于经历类似动力学的其他模型。我们的结果将为利用引力波观测寻找新的物理和暗物质提供新的途径，并提高我们对快子粒子产生及其对轴子暗物质丰度和性质的影响的理解。

Axions and axion like particles (ALPs) are motivated both as a solution of the strong CP problem and as candidates for dark matter. Recently we have shown that gravitational waves sourced by axion dynamics in the early universe may be detectable in future gravitational wave experiments. This is possible if the axion couples to a dark photon, which then experiences a tachyonic instability while the axion rolls towards the origin of its potential. The goal of this proposal is to further explore this possibility, by i) determining the region of axion parameter space that can be probed using gravitational waves, ii) performing more precise numerical simulations of the production mechanism, iii) developing methods to distinguish the axion signal from other sources of gravitational waves and iv) applying it to other models which undergo similar dynamics. Our results will provide new ways of searching for new physics and dark matter using gravitational wave observations, and improve our understanding of tachyonic particle production and its impact on the axion dark matter abundance and properties.