标题： 降低进动黑洞双星的轨道偏心率 显示英文标题

标题： Reducing orbital eccentricity of precessing black-hole binaries

摘要： 构建一般双黑洞演化的初始条件，同时避免出现虚假偏心率，仍然是数值相对论模拟的一大挑战。 这个问题可以通过应用一种去偏心化程序来克服，该程序包括让双黑洞系统演化几个轨道周期，估算偏心率，然后修正初始条件。 自旋的存在会使这个过程复杂化。 根据后牛顿理论的预测，自旋-自旋相互作用和进动阻止了双黑洞系统沿着球对称轨道的绝热序列移动，导致径向分离和轨道频率出现振荡。 然而，由自旋引起的振荡大约发生在轨道频率的两倍，因此可以将其与发生在接近轨道频率的初始虚假偏心率区分开来。 我们开发了一种基于轨道频率导数的新去偏心化程序，并发现当存在中等大小的自旋时，它可以将轨道频率测量到的偏心率降低到小于0.0001。 我们使用质量比为1.5和3、自旋大小为0.5以及不同自旋方向的双黑洞数值相对论模拟测试了这一新程序。 数值模拟显示，在大约两倍轨道频率处的动力学中存在自旋诱导的振荡。 类似频率的振荡也出现在主导模式的引力波相位和频率中。 显示英文摘要

摘要： Building initial conditions for generic binary black-hole evolutions without initial spurious eccentricity remains a challenge for numerical-relativity simulations. This problem can be overcome by applying an eccentricity-removal procedure which consists in evolving the binary for a couple of orbits, estimating the eccentricity, and then correcting the initial conditions. The presence of spins can complicate this procedure. As predicted by post-Newtonian theory, spin-spin interactions and precession prevent the binary from moving along an adiabatic sequence of spherical orbits, inducing oscillations in the radial separation and in the orbital frequency. However, spin-induced oscillations occur at approximately twice the orbital frequency, therefore they can be distinguished from the initial spurious eccentricity, which occurs at approximately the orbital frequency. We develop a new removal procedure based on the derivative of the orbital frequency and find that it is successful in reducing the eccentricity measured in the orbital frequency to less than 0.0001 when moderate spins are present. We test this new procedure using numerical-relativity simulations of binary black holes with mass ratios 1.5 and 3, spin magnitude 0.5 and various spin orientations. The numerical simulations exhibit spin-induced oscillations in the dynamics at approximately twice the orbital frequency. Oscillations of similar frequency are also visible in the gravitational-wave phase and frequency of the dominant mode.