On the newtonian and spin-induced perturbations felt by the stars orbiting around the massive black hole in the galactic center
On the newtonian and spin-induced perturbations felt by the stars orbiting around the massive black hole in the galactic center
复制标题
关于围绕银河系中心大质量黑洞运行的恒星所感受到的牛顿扰动和自旋引起的扰动
DOI：
10.3847/1538-4357/834/2/198
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发表时间：
2017
影响因子：
4.9
通讯作者：
Iorio Lorenzo
中科院分区：
文献类型：
--
作者：
Zhang Fupeng;Iorio Lorenzo
在银河中心发现的 S 星预计将为它们所轨道的大质量黑洞 (MBH) 的克尔度量提供独特的动力学测试。为了获得对其自旋和相关相对论效应的公正测量，全面了解MBH周围恒星和恒星遗迹的引力扰动是非常必要的。在这里，我们研究了由于单个物体或一组扰动物体的自旋引起的相对论效应和牛顿引力对典型目标恒星的可观测量的扰动，即视轨道运动和红移。我们发现，在大多数情况下，可观测量的牛顿扰动主要归因于目标星的扰动轨道周期，而不是牛顿轨道进动。观察当前检测到的恒星 S2/S0-2，我们发现其自旋引起的效应很可能被恒星 S0-102 本身的引力摄动所掩盖。我们还研究并讨论了位于当前探测到的轨道内的假设 S 星的牛顿扰动。通过考虑中心 MBH 附近的许多可能的恒星分布，我们发现，如果 MBH 处于最大自旋状态，则对于轨道半长轴小于 100-400 au 的目标恒星，自旋引起的视位置和红移效应在恒星扰动中占主导地位。我们的结果表明，原则上，恒星扰动可以被消除，因为它们的形态与相对论克尔型特征不同。
The S-stars discovered in the Galactic center are expected to provide unique dynamical tests of the Kerr metric of the massive black hole (MBH) that they orbit. In order to obtain unbiased measurements of its spin and the related relativistic effects, a comprehensive understanding of the gravitational perturbations of the stars and stellar remnants around the MBH is quite essential. Here, we study the perturbations on the observables of a typical target star, i.e., the apparent orbital motion and the redshift, due to both the spin-induced relativistic effects and the Newtonian attractions of a single object or a cluster of disturbing objects. We find that, in most cases, the Newtonian perturbations on the observables are mainly attributed to the perturbed orbital period of the target star rather than the Newtonian orbital precessions. Looking at the currently detected star S2/S0-2, we find that its spin-induced effects are very likely obscured by the gravitational perturbations from the star S0-102 alone. We also investigate and discuss the Newtonian perturbations on a hypothetical S-star located inside the orbits of those currently detected. By considering a number of possible stellar distributions near the central MBH, we find that the spin-induced effects on the apparent position and redshift dominate over the stellar perturbations for target stars with orbital semimajor axis smaller than 100–400 au if the MBH is maximally spinning. Our results suggest that, in principle, the stellar perturbations can be removed because they have morphologies distinct from those of the relativistic Kerr-type signatures.