论文标题
重新访问恒星轨道和sgr a $^*$ quadrupole时刻
Revisiting Stellar Orbits and the Sgr A$^*$ Quadrupole Moment
论文作者
论文摘要
原则上，可以通过测量SGR的旋转和四极矩，并在整个时期测量SGR a $^*$的四杆矩时，在银河系中心测试“无毛”定理。与原始方法相反，我们显示了为什么仅通过在半轨道上测量进动角来测量一个恒星的观测值可以测试无发的定理。有观察性和理论原因可以期望S-Star迅速旋转，并且我们通过自旋 - 曲面耦合（Mathisson-Papapetrou-Dixon方程的领先表现）量化了恒星自旋的作用，对未来的四核测量值。我们发现它们通常会遇到几个百分点的顺序错误，但是对于某些轨道参数，错误可能更高。我们重新检查了可能阻碍未来四极杆测量值的天体物理噪声源的更普遍的问题，并发现明智的可测量进动角选择通常可以消除单个噪声源。我们得出了可观察物的最佳组合，以消除质量进动的大噪声源，由于恒星自旋而引起的自旋曲率耦合的新型噪声以及恒星电位中瞬时四极力矩产生的更复杂的噪声源。
The "no-hair" theorem can, in principle, be tested at the center of the Milky Way by measuring the spin and the quadrupole moment of Sgr A$^*$ with the orbital precession of S-stars, measured over their full periods. Contrary to the original method, we show why it is possible to test the no-hair theorem using observations from only a single star, by measuring precession angles over a half-orbit. There are observational and theoretical reasons to expect S-stars to spin rapidly, and we have quantified the effect of stellar spin, via spin-curvature coupling (the leading-order manifestation of the Mathisson-Papapetrou-Dixon equations), on future quadrupole measurements. We find that they will typically suffer from errors of order a few percentage points, but for some orbital parameters, the error can be much higher. We re-examine the more general problem of astrophysical noise sources that may impede future quadrupole measurements, and find that a judicious choice of measurable precession angles can often eliminate individual noise sources. We have derived optimal combinations of observables to eliminate the large noise source of mass precession, the novel noise of spin-curvature coupling due to stellar spin, and the more complicated noise source arising from transient quadrupole moments in the stellar potential.
