Axion-photon conversion in 3D media and astrophysical plasmas
Axion-photon conversion in 3D media and astrophysical plasmas
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DOI：
10.1088/1475-7516/2023/12/031
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发表时间：
2023-07
影响因子：
6.4
通讯作者：
J. McDonald;B. Garbrecht;P. Millington
中科院分区：
文献类型：
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作者：
J. McDonald;B. Garbrecht;P. Millington
由于轴子现在是暗物质的主要候选者，了解它们的间接天体物理特征是至关重要的。关键是在磁化的天体物理等离子体中，轴子产生光子。虽然一维空间中轴子-光子混合的简单公式在几十年前就已经被勾画出来，但最近人们对任意三维等离子体中这一过程的稳健计算重新产生了兴趣。这些计算对于理解中子星中轴子暗物质转换产生的射电产生至关重要，这可能导致用目前的望远镜或未来的搜索，例如通过SKA进行间接轴子暗物质探测。本文推导了磁化等离子体中的输运方程。这些方程描述了由于轴子到光子的共振转换，光子在任意3D介质中的产生和传播。它们也完全包含了光子的折射，我们没有发现任何证据来证明我们猜想的退相现象。我们的结果没有困扰以前计算的分歧，我们的动力学理论描述提供了光线跟踪和产生机制之间的直接联系。这些结果标志着朝着解决近年来间接寻找轴子的主要公开问题之一迈出了重要的一步，即如何计算任意3D等离子体中轴子的光子产生率。
With axions now a primary candidate for dark matter, understanding their indirect astrophysical signatures is of paramount importance. Key to this is the production of photons from axions in magnetised astrophysical plasmas. While simple formulae for axion-photon mixing in 1D have been sketched several decades ago, there has recently been renewed interest in robust calculations for this process in arbitrary 3D plasmas. These calculations are vital for understanding, amongst other things, the radio production from axion dark matter conversion in neutron stars, which may lead to indirect axion dark matter detection with current telescopes or future searches, e.g., by the SKA. In this paper, we derive the relevant transport equations in magnetised plasmas. These equations describe both the production and propagation of photons in an arbitrary 3D medium due to the resonant conversion of axions into photons. They also fully incorporate the refraction of photons, and we find no evidence for a conjectured phenomenon of dephasing. Our result is free of divergences which plagued previous calculations, and our kinetic theory description provides a direct link between ray tracing and the production mechanism. These results mark an important step toward solving one of the major open questions concerning indirect searches of axions in recent years, namely how to compute the photon production rate from axions in arbitrary 3D plasmas.