标题： 向建模AR Sco：广义粒子动力学和强辐射反应区域 显示英文标题

标题： Towards Modelling AR Sco: Generalised Particle Dynamics and Strong Radiation-Reaction Regimes

摘要： 相对论等离子体的数值模拟在计算资源可用的情况下变得更加可行、流行，并对各种天体物理源至关重要。由于与之相关的极端电磁场和粒子洛伦兹因子，高精度粒子动力学的必要性在脉冲星建模中尤其突出。在粒子动力学中包含辐射反作用力会使问题更加复杂，但对于这些极端天体物理源来说是至关重要的。我们还意识到，对于AR Sco（第一个白矮星脉冲星）提出的磁镜和粒子注入模型，这种建模是必要的。本文展示了使用高阶显式数值积分器结合自适应时间步长方法来求解包含辐射反作用力的完整粒子动力学的好处。我们表明，在标准测试场景中，即各种均匀$E$-和$B$-场以及静态偶极子$B$-场的组合情况下，我们使用的方案在准确性上与标准辛积分器相当，并且在极端场情况下表现更优。我们表明，由于我们实现的自适应时间步长，高阶方案在计算时间上有显著改进，尤其是在非均匀场情况和包含辐射反应的情况下，粒子回旋半径迅速变化。在平衡准确性和计算时间时，我们确定自适应Dormand-Prince八阶方案最适合我们的用例。我们使用的方案在描述粒子动力学时保持了准确性和稳定性，并指出带电粒子如何进入辐射反作用平衡并符合分析的亚里士多德电动力学预期。 显示英文摘要

摘要： Numerical simulations of relativistic plasmas have become more feasible, popular, and crucial for various astrophysical sources with the availability of computational resources. The necessity for high-accuracy particle dynamics is especially highlighted in pulsar modelling due to the extreme associated electromagnetic fields and particle Lorentz factors. Including the radiation-reaction force in the particle dynamics adds even more complexity to the problem, but is crucial for such extreme astrophysical sources. We have also realised the need for such modelling concerning magnetic mirroring and particle injection models proposed for AR Sco, the first white dwarf pulsar. This paper demonstrates the benefits of using higher-order explicit numerical integrators with adaptive time step methods to solve the full particle dynamics with radiation-reaction forces included. We show that for standard test scenarios, namely various combinations of uniform $E$- and $B$-fields and a static dipole $B$-field, the schemes we use are equivalent to and in extreme field cases outperform standard symplectic integrators in accuracy. We show that the higher-order schemes have massive computational time improvements due to the adaptive time steps we implement, especially in non-uniform field scenarios and included radiation reaction where the particle gyro-radius rapidly changes. When balancing accuracy and computational time, we identified the adaptive Dormand-Prince eighth-order scheme to be ideal for our use cases. The schemes we use maintain accuracy and stability in describing the particle dynamics and we indicate how a charged particle enters radiation-reaction equilibrium and conforms to the analytic Aristotelian Electrodynamics expectations.