标题： 内部结构和测试粒子的圆轨道 显示英文标题

标题： Internal structures and circular orbits for test particles

摘要： 我们探讨了测试粒子的内部结构如何影响其在带有或不带有宇宙学常数的Kerr黑洞周围的赤道稳定圆轨道。为此，我们首先明确写出在极-偶极-四极近似下测试粒子的运动方程，并将四极矩张量指定为自旋引起的模型。然后，我们计算处于稳定圆轨道上的粒子的特征量——半径、角动量、能量、角速度和影响参数。一旦采用极-偶极-四极近似，我们发现对于处于最内稳定圆轨道上的粒子，除了角速度外，所有特征量都相对于极-偶极情况更大。相反，对于处于最外稳定圆轨道上的粒子，该轨道仅存在于时空背景为渐近de Sitter的情况下，此时半径变小，而其他所有量都变大。 显示英文摘要

摘要： We explore how the internal structure of a test particle affects its equatorial stable circular orbits around the Kerr black hole with or without a cosmological constant. To this end, we first explicitly write equations of motion for a test particle in the pole-dipole-quadrupole approximation specifying the quadrupole momentum tensor to a spin-induced model. Then we calculate characteristic quantities -- radius, angular momentum, energy, angular velocity, and impact parameter -- for the particles on the stable circular orbits. Once the pole-dipole-quadrupole approximation is taken, we find that for a particle on an innermost stable circular orbit, all characteristic quantities, except the angular velocity, become greater relative to the pole-dipole case. In contrast, for a particle on an outermost stable circular orbit, which only exists in the case of the spacetime background being asymptotically de Sitter, it is the radius that becomes smaller while all other quantities become greater.