论文标题
磁流失动力学预测轴突转换的重尾分布
Magnetohydrodynamics predicts heavy-tailed distributions of axion-photon conversion
论文作者
论文摘要
磁性天体物理环境中轴心状颗粒（阿尔卑斯山）和光子的相互转换为寻找阿尔卑斯山提供了有希望的途径。迄今为止，在光阿尔卑斯山上最强的限制使用星系簇作为ALP-Photon转换器。但是，这些研究传统上依赖于群集磁场的简单模型，而最先进的是高斯随机场（GRFS）。我们介绍了来自专用磁性水力动力学（MHD）模拟的ALP-Photon转换的首次系统研究，我们将其与GRF模型进行了比较。对于GRF，我们从分析得出固定能量下转换比的分布，发现它遵循指数定律。我们发现，MHD模型与典型的小振幅混合物的指数定律一致，但对于稀有和大型混合而表现出明显的沉重尾巴。我们解释了非高斯的特征，例如〜相干结构和MHD磁场中的局部尖峰是如何负责重尾巴的。我们的结果表明，使用GRF放置在阿尔卑斯山上的限制是可靠的。
The interconversion of axionlike particles (ALPs) and photons in magnetised astrophysical environments provides a promising route to search for ALPs. The strongest limits to date on light ALPs use galaxy clusters as ALP-photon converters. However, such studies traditionally rely on simple models of the cluster magnetic fields, with the state-of-the-art being Gaussian random fields (GRFs). We present the first systematic study of ALP-photon conversion in more realistic, turbulent fields from dedicated magnetohydrodynamic (MHD) simulations, which we compare with GRF models. For GRFs, we analytically derive the distribution of conversion ratios at fixed energy and find that it follows an exponential law. We find that the MHD models agree with the exponential law for typical, small-amplitude mixings but exhibit distinctly heavy tails for rare and large mixings. We explain how non-Gaussian features, e.g.~coherent structures and local spikes in the MHD magnetic field, are responsible for the heavy tail. Our results suggest that limits placed on ALPs using GRFs are robust.
