气体在维持恒星星系准定常螺旋结构中的作用
The Role of Gas In Maintaining Quasi-Steady Spiral Structure In Stellar Disks
摘要：
我们使用高分辨率的光滑粒子流体动力学（SPH）模拟，处理气体，恒星和暗物质的演化自洽的螺旋结构的动力学演化的孤立星系的恒星盘。我们的研究集中在恒星盘中的自激螺旋结构的问题，并调查之间的动力学耦合的冷，耗散的气体成分和恒星组件。我们发现，角动量传输从气体到恒星内部的共转导致一个大致时间稳定的螺旋结构的恒星盘。为了明确这一点，我们将这些结果与不包括能够辐射冷却和耗散能量的冷气体成分的其他相同模拟进行对比，并发现螺旋结构在初始时，在不包括气体的模拟中更快地消失。我们还采用了一个标准的恒星形成处方转换成恒星的气体，并发现我们的研究结果适用于典型的气体消耗时间尺度，符合肯尼卡特-施密特关系。因此，我们属性的长寿命的大致时间稳定的螺旋结构在恒星盘的气体和恒星之间的动力学耦合和由此产生的扭矩，自引力气体盘能够施加在恒星上，由于无碰撞和耗散组件之间的方位角相移。
英文摘要：
We study the dynamical evolution of spiral structure in the stellar disks of isolated galaxies using high resolution Smoothed Particle Hydrodynamics (SPH) simulations that treat the evolution of gas, stars, and dark matter self-consistently. We focus this study on the question of self-excited spiral structure in the stellar disk and investigate the dynamical coupling between the cold, dissipative gaseous component and the stellar component. We find that angular momentum transport from the gas to the stars inside of corotation leads to a roughly time-steady spiral structure in the stellar disk. To make this point clear, we contrast these results with otherwise identical simulations that do not include a cold gaseous component that is able to cool radiatively and dissipate energy, and find that spiral structure, when it is incipient, dies out more rapidly in simulations that do not include gas. We also employ a standard star formation prescription to convert gas into stars and find that our results hold for typical gas consumption time scales that are in accord with the Kennicutt-Schmidt relation. We therefore attribute the long-lived roughly time steady spiral structure in the stellar disk to the dynamical coupling between the gas and the stars and the resultant torques that the self-gravitating gaseous disk is able to exert on the stars due to an azimuthal phase shift between the collisionless and dissipative components.
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