标题： 轴子云由于轴子-光子转换在多极背景磁场下的衰变 显示英文标题

标题： Axion Cloud Decay due to the Axion-photon Conversion with Multi-pole Background Magnetic Fields

摘要： 我们考虑由于轴子-光子转换导致的轴子云衰变，在多极背景磁场下。 我们关注轴子场配置的$\ell=m=1$和$n=2$模式，因为它们与超辐射不稳定性相关的增长率最大。 在存在背景多极磁场的情况下，轴子场可以通过轴子-光子耦合转化为电磁场。 然后通过逐次近似计算由于转化光子耗散导致的衰变率。 我们发现衰变率显著依赖于表征背景磁场的环向量子数，并且可以与或大于超辐射不稳定性增长速率。 显示英文摘要

摘要： We consider axion cloud decay due to the axion-photon conversion with multi-pole background magnetic fields. We focus on the $\ell=m=1$ and $n=2$ mode for the axion field configuration since it has the largest growth rate associated with superradiant instability. Under the existence of a background multi-pole magnetic field, the axion field can be converted into the electromagnetic field through the axion-photon coupling. Then the decay rate due to the dissipation of the converted photons is calculated in a successive approximation. We found that the decay rate is significantly dependent on the azimuthal quantum number characterizing the background magnetic field, and can be comparable to or larger than the growth rate of the superradiant instability.