We perform local $N$-body simulations of disk galaxies and investigate the evolution of spiral arms. We calculate the time autocorrelation of the surface density of spiral arms and find that the typical evolution timescale is described by the epicycle period. We investigate the distribution of the orbital elements of stars and find that in spiral arms the epicycle motions of stars are in phase while the spatial distribution of the guiding center is nearly uniform. These facts clearly show that the phase synchronization of the epicycle motion takes place, which is theoretically predicted by the swing amplification.

中文翻译：

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通过摆动放大在银河螺旋臂中进行相干恒星运动

我们对盘状星系进行局部 $N$-body 模拟并研究旋臂的演化。我们计算了旋臂表面密度的时间自相关，发现典型的演化时间尺度由本轮周期描述。我们研究了恒星轨道元素的分布，发现在旋臂中恒星的本轮运动是同相的，而引导中心的空间分布几乎是均匀的。这些事实清楚地表明本轮运动的相位同步发生了，这在理论上是由摆动放大预测的。