旋进星系棒模型中的翘曲证据
Warp evidences in precessing galactic bar models
摘要：
大多数星系从侧面看时都有一个扭曲的形状。到目前为止，这种奇怪形式的原因还不完全清楚，在这项工作中，我们应用动力系统工具来解释它。从一个简单的，但现实的，由一个酒吧和一个磁盘形成的模型开始，我们研究了系统的角动量和它的角速度之间的小偏差所产生的效果。为此，进动模型的开发和考虑，假设酒吧的行为像一个刚体。在检查了杆内的周期轨道仍然是内部系统的骨架之后，即使在对势施加岁差之后，我们计算了不稳定周期轨道的不变流形，这些不稳定周期轨道离开杆端部的平衡点，以获得它们弯曲形状的证据。众所周知，与这些周期轨道相关的不变流形驱动棒星系的臂和环，并构成这些积木的骨架。从侧面观察它们，我们发现这些流形呈现出与观测中所识别的一样的扭曲形状。最后，进行了测试粒子模拟，以确定恒星如何受到所施加的岁差的影响，从而证实了所获得的理论结果。
英文摘要：
Most galaxies have a warped shape when they are seen from an edge-on point of view. The reason for this curious form is not completely known so far and in this work we apply dynamical system tools to contribute to its explanation. Starting from a simple, but realistic, model formed by a bar and a disc, we study the effect produced by a small misalignment between the angular momentum of the system and its angular velocity. To this end, a precession model is developed and considered, assuming that the bar behaves like a rigid body. After checking that the periodic orbits inside the bar keep being the skeleton of the inner system, even after inflicting a precession to the potential, we compute the invariant manifolds of the unstable periodic orbits departing from the equilibrium points at the ends of the bar to get evidences of their warped shapes. As it is well known, the invariant manifolds associated with these periodic orbits drive the arms and rings of barred galaxies and constitute the skeleton of these building blocks. Looking at them from a side-on viewpoint, we find that these manifolds present warped shapes as those recognized in observations. Lastly, test particle simulations have been performed to determine how the stars are affected by the applied precession, confirming this way the theoretical results obtained.
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