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arXiv 2103.12082hep-phastro-ph.CO
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电磁场中轴子星的偶极辐射及超越

Dipole Radiation and Beyond from Axion Stars in Electromagnetic Fields

Mustafa A. Amin, Andrew J. Long, Zong-Gang Mou, Paul Saffin

摘要:

我们研究了在外部电磁场存在下,从相干振荡的、空间局部化的轴子场(轴子和轴子星)中产生光子。我们描绘了不同的定性行为的光子光度的一个有效的无量纲耦合参数构造出的轴子光子耦合,场振幅,振荡频率和半径的轴子星。对于这种无量纲耦合的小值,我们提供了一个一般的解析公式的偶极辐射场和光子光度每立体角,包括强烈依赖于配置的半径。对于中到大的耦合,我们报告的非单调行为的光度与耦合强度的存在下,外部磁场。在亮度随耦合强度的初始上升之后,我们看到在中等大的耦合下的抑制(与偶极辐射近似相比是一个数量级或更多)。在足够大的耦合,我们发现一个过渡到制度的指数增长的光度由于参数共振。我们进行3+1维晶格模拟的轴子电动力学,在小和大的耦合,包括非微扰效应的参数共振,以及在必要时的反反应效应。我们还讨论了介质(等离子体)的影响,导致共振轴子光子转换,相干性的孤子的相关性,以及我们的结果在天体物理和宇宙学设置的影响。

英文摘要:

We investigate the production of photons from coherently oscillating, spatially localized clumps of axionic fields (oscillons and axion stars) in the presence of external electromagnetic fields. We delineate different qualitative behaviour of the photon luminosity in terms of an effective dimensionless coupling parameter constructed out of the axion-photon coupling, and field amplitude, oscillation frequency and radius of the axion star. For small values of this dimensionless coupling, we provide a general analytic formula for the dipole radiation field and the photon luminosity per solid angle, including a strong dependence on the radius of the configuration. For moderate to large coupling, we report on a non-monotonic behavior of the luminosity with the coupling strength in the presence of external magnetic fields. After an initial rise in luminosity with the coupling strength, we see a suppression (by an order of magnitude or more compared to the dipole radiation approximation) at moderately large coupling. At sufficiently large coupling, we find a transition to a regime of exponential growth of the luminosity due to parametric resonance. We carry out 3+1 dimensional lattice simulations of axion electrodynamics, at small and large coupling, including non-perturbative effects of parametric resonance as well as backreaction effects when necessary. We also discuss medium (plasma) effects that lead to resonant axion to photon conversion, relevance of the coherence of the soliton, and implications of our results in astrophysical and cosmological settings.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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