发表机构
Zhejiang University of Technology（浙江工业大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本文研究克尔-贝托蒂-罗宾逊时空中，外磁场通过引力反作用形变时空、偶极与磁场直接耦合两种通道，对磁化粒子轨道及近视界碰撞的影响，修正了巴尼亚多斯-西尔克-韦斯特机制的相关结果。
AI 中文摘要
强磁场通过两个不同通道影响粒子动力学：引力反作用使时空发生形变，而与固有磁矩的直接耦合则取决于磁场与偶极子的相对取向。我们通过研究精确克尔-贝托蒂-罗宾逊时空中电中性磁化粒子的赤道轨道与近视界碰撞，来区分这些效应。场诱导的几何形变会移动转折点和圆轨道区域，并可消除有限的有效势阱及其束缚轨道；即便没有直接偶极耦合，它也能抵消克尔近日点进动，产生有限半径的零进动轨道。直接偶极耦合会打破磁场反转下的对称性，并以取向依赖的方式移动最内稳定圆轨道的半径、能量与角动量。然而，这些轨道分支的形式上的极端相对论端点仍由背景几何固定，并趋近于类光圆轨道。在巴尼亚多斯-西尔克-韦斯特机制中，两种磁效应都会改变有限半径的势垒，从而影响临界粒子到达近视界碰撞区域的能力。在本文所考察的代表性非零场情形中，从无穷远释放的恰好临界粒子在抵达极值视界前会被阻挡，不过临界粒子与普通粒子间的局域容许碰撞仍可产生无界质心能量；有限偶极耦合会移动势垒，但不会改变近视界发散的主导项。在非极值视界附近，恰好临界粒子被排除，碰撞能量保持有限。
英文摘要
Strong magnetic fields affect particle dynamics through two distinct channels: gravitational backreaction deforms the spacetime, while direct coupling to an intrinsic magnetic moment depends on the relative orientation of the field and the dipole. We disentangle these effects by studying equatorial orbits and near-horizon collisions of electrically neutral magnetized particles in the exact Kerr--Bertotti--Robinson spacetime. The field-induced geometric deformation shifts turning points and circular-orbit domains and can eliminate a finite effective-potential well together with its bound orbits. Even without direct dipole coupling, it can also offset the Kerr periapsis advance and produce a finite-radius zero-precession orbit. Direct dipole coupling breaks the symmetry under magnetic-field reversal and shifts the radius, energy, and angular momentum of the innermost stable circular orbit in an orientation-dependent manner. The formal ultrarelativistic endpoints of these orbit branches, however, remain fixed by the background geometry and approach circular null orbits. In the Bañados--Silk--West mechanism, both magnetic effects modify finite-radius potential barriers and hence the ability of a critical particle to reach the near-horizon collision region. In the representative nonzero-field cases examined here, an exactly critical particle released from infinity is blocked before reaching an extremal horizon, although a locally admissible collision between critical and usual particles can still produce unbounded center-of-mass energy. Finite dipole coupling shifts the barriers but does not change the leading near-horizon divergence. Near a nonextremal horizon, an exactly critical particle is excluded and the collision energy remains finite.
Comments21 pages, 13 figures, 5 tables
