论文标题
速度空间中的弯曲波：第一次看事物样本
Bending Waves in Velocity Space: a First Look at the THINGS sample
论文作者
论文摘要
即使在附近的椎间盘星系中，由于其子KPC弯曲振幅，检测弯曲波是一项高度挑战的任务。但是，模拟表明，像圆盘星系一样的银河系的谐波弯曲与测得的视线（LOS）速度的谐波波动有关，并且可以被视为显现弯曲波的运动学标志。在这里，我们在\ hi圆盘中寻找类似的弯曲波的运动学特征，因为它们延伸到了光射线射频之外。 我们对样品的附近六个螺旋星系的\ HI LOS残留速度场进行了多极分析，该速度触发了弯曲波诱导的速度峰。这使我们能够确定星系中存在的不同弯曲模式的径向位置和振幅。我们发现，所有样品盘都显示出几种低阶弯曲模式叠加的运动学标志，这表明弯曲波是常见的现象。发现已确定的速度峰为模式$ M = 2,3 $和$ 4 $，幅度不超过15 km s $^{ - 1} $，并分布在整个\ hi光盘中。有趣的是，它们似乎集中在宿主星系的光学边缘附近。另外，$ m = 2 $似乎比其他两种模式更常见。
Detection of bending waves is a highly challenging task even in nearby disc galaxies due to their sub-kpc bending amplitudes. However, simulations show that the harmonic bending of a Milky Way like disc galaxy is associated with a harmonic fluctuation in the measured line of sight (los) velocities as well, and can be regarded as a kinematic signature of a manifested bending wave. Here, we look for similar kinematic signatures of bending waves in \HI discs, as they extend to much beyond the optical radii. We present a multipole analysis of the \HI los residual velocity fields of six nearby spiral galaxies from the THINGS sample, which uncovers the bending wave-induced velocity peaks. This allows us to identify the radial positions and amplitudes of the different bending modes present in the galaxies. We find that all of our sample discs show a combined kinematic signature of superposition of a few lower-order bending modes, suggesting that bending waves are a common phenomenon. The identified velocity peaks are found to be of modes $m=2,3$ and $4$, not more than 15 km s$^{-1}$ in amplitude and spread across the entire \HI disc. Interestingly, they appear to be concentrated near the optical edge of their host galaxies. Also, $m=2$ appears to be more common than the other two modes.
