由径向轨道不稳定性形成的尖点三轴系统的性质
The properties of cuspy triaxial systems formed due to the radial-orbit instability
摘要：
上下文我们已经研究了三轴最终模型的结构和运动学形成的径向轨道不稳定性，从一组平衡各向异性的Osipkov-Merritt型的球形系统。目标。我们表明，不稳定性是一种自然的方式来建立非球形系统，因此可以被认为是一种新的技术，用于构建平衡$N$体模型。方法.模型的动力学演化是通过Dehnen的公共代码gyrfacON数值跟踪的。结果我们发现，尽管系统被剧烈地重新排列成三轴构型，并得到了新的标度长度，但各种初始球形模型的密度分布形状并没有改变。尖被认为是一个不变的功能，这样的重排。从一个不稳定的球形$γ$模型出发，得到了一个具有相同尖点的三轴系统。最终产物在大半径处是各向异性的，并且具有Osipkov-Merrit型的各向异性轮廓。各向同性核的大小一旦重新缩放对应于边缘稳定的$γ$ -祖细胞的值，并且几乎与不稳定的起始点无关。结论.我们的结论是，最终产品达到一个新的稳定状态，并具有相当可预测的属性。它们可以作为描述椭圆星系和星系球的平衡模型。它们也可用于处理多部件系统的$N$ -体模拟。
英文摘要：
Context. We have investigated the structure and kinematics of triaxial final models formed due to radial-orbit instability from a set of equilibrium anisotropic spherical systems of the Osipkov-Merritt type. Aims. We show that the instability is a natural way to build nonspherical systems and thus can be considered as a new technique for constructing equilibrium $N$-body models. Methods. The dynamical evolution of the models was followed numerically by means of the Dehnen's public code gyrfacON. Results. We found that the shape of the density profiles for various initial spherical models didn't change despite of the systems were drastically rearranged into triaxial configurations and had got the new scale lengths. The cusp was found to be an invariant feature of such a rearranging. Starting from a certain unstable spherical $γ$-model we obtain a triaxial system with the same cusp. The end-products are anisotropic at large radii and have anisotropy profiles of the Osipkov-Merrit type. The size of the isotropic core once rescaled corresponds to the value of marginally stable $γ$-progenitors and is almost independent of the unstable starting point. Conclusions. We conclude that the end-products reach a new steady state and have quite predictable properties. They can be used as equilibrium models to describe the elliptical galaxies and bulges. They also can be incorporated in $N$-body simulations deal with multicomponent systems.
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