旋臂放大与盖亚相位螺旋
Swing Amplification and the Gaia Phase Spirals
AI总结：
本文在剪切盒框架下将密度波摆动放大理论推广到垂直方向，解析研究了盘面对对称与反对称外部激发的响应，揭示了自引力在形成单臂或双臂相位螺旋中的关键作用，并质疑了基于运动学推断盖亚相位螺旋年龄的简单方法。
摘要：
我们在剪切盒近似的框架内探讨了恒星盘面内动力学与垂直动力学之间的相互作用。Julian和Toomre曾利用剪切片证明，前导密度波在摆动为尾随波的过程中会被放大。我们将他们的形式体系扩展到垂直于盘面的维度，并获得了盘面对脉冲式外部激发响应的显式解。关于中平面对称的激发会产生密度/呼吸波，以及在垂直相空间平面中的双臂相位螺旋。另一方面，关于中平面反对称的激发则会导致弯曲波和单臂相位螺旋。无论哪种情况，自引力在驱动扰动演化以及决定随后形成的螺旋的振幅和螺距角方面都起着关键作用。我们还表明，当盘面受到共转云团的激发时，它会在云团的尾迹中形成静态相位螺旋。这些结果对用于确定盖亚巡天中所见相位螺旋年龄的简单运动学论证提出了质疑。
英文摘要：
We explore the interplay between in-plane and vertical dynamics in stellar discs within the framework of the shearing box approximation. Julian and Toomre used the shearing sheet to show that leading density waves are amplified as they swing into a trailing ones. We extend their formalism into the dimension perpendicular to the disc and obtain explicit solutions for the response of a disc to an impulsive, external excitation. An excitation that is is symmetric about the mid plane produces a density/breathing wave as well as two-armed phase spirals in the vertical phase space plane. On the other hand, an excitation that is antisymmetric about the mid plane leads to a bending wave and single-armed phase spirals. In either case, self-gravity plays a crucial role in driving the evolution of the disturbance and determining the amplitude and pitch angle of the ensuing spirals. We also show that when the disc is excited by a co-rotating cloud, it develops stationary phase spirals in the wake of the cloud. The results call into question simple kinematic arguments that have been used to determine the age of the phase spirals seen in the Gaia survey
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