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arXiv 1508.06293astro-ph.HEgr-qc
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利用恒星轨道运动检验银心大质量黑洞的Kerr度规:完全广义相对论处理

On Testing the Kerr Metric of the Massive Black Hole in the Galactic Center via Stellar Orbital Motion: Full General Relativistic Treatment

Fupeng Zhang, Youjun Lu, Qingjuan Yu

摘要:

银河系中心的S星对银河系中心大质量黑洞的自旋具有独特的动力学约束作用。在本文中,我们开发了一个快速的完整的广义相对论方法,同时限制MBH的质量,自旋和自旋方向,考虑恒星的运动和光子从恒星到遥远的观察者的传播。假设一些恒星的例子,我们证明了自旋对恒星投影轨迹和红移曲线的影响依赖于自旋的大小和方向。对于自旋方向明显不同的情况,整个轨道上的最大效应可能相差一个因子,最高可达一个数量级以上。采用马尔可夫链蒙特卡罗拟合技术,我们证明,如果S_0 ~(-2)/S_2接近1,则在~ 45年的周期内,GC MBH的自旋很可能被S_0 ~(-2)/S_2很好地约束,天体测量和光谱精度(σ_p,σ_Z)可达(10 μ as,1 km/s)。与此同时,从太阳到GC的距离和MBH质量也可以被限制到前所未有的精度(0.01%-0.1%)。如果存在一颗半长轴明显小于S 0 -2/S2,偏心率大于S 0 -2/S2的恒星,那么即使该恒星的自旋很小(> 0.2),在(sigma_p,sigma_Z)~(10 μ as,1 km/s)的条件下,MBH的自旋也可以在<~ 10年的周期内得到高精度的约束。

英文摘要:

The S-stars in the Galactic center (GC) are anticipated to provide unique dynamical constraint on the spin of the GC massive black hole (MBH). In this paper, we develop a fast full general relativistic method to simultaneously constrain the MBH mass, spin, and spin direction by considering both the motion of a star and the propagation of photons from the star to a distant observer. Assuming some example stars, we demonstrate that the spin-induced effects on the projected trajectory and redshift curve of a star depend on both the value and the direction of the spin. The maximum effects over a full orbit can differ by a factor upto more than one order of magnitude for cases with significantly different spin directions. Adopting the Markov Chain Monte Carlo fitting technique, we illustrate that the spin of the GC MBH is likely to be well constrained by using the motion of S0-2/S2 over a period of ~45yr if it is close to one and the astrometric and spectroscopic precisions (sigma_p,sigma_Z) can be as high as (10muas, 1km/s). In the mean time, the distance from the sun to the GC and the MBH mass can also be constrained to an unprecedented accuracy (0.01%-0.1%). If there exists a star with semimajor axis significantly smaller than that of S0-2/S2 and eccentricity larger than that of S0-2/S2, the MBH spin can be constrained with high accuracy over a period of <~10yr for (sigma_p,sigma_Z) ~ (10muas,1km/s), even if the spin is only moderately large (>~0.2).

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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