THE ORBITAL STRUCTURE OF TRIAXIAL GALAXIES WITH FIGURE ROTATION
THE ORBITAL STRUCTURE OF TRIAXIAL GALAXIES WITH FIGURE ROTATION
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DOI：
10.1088/0004-637x/728/2/128
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发表时间：
2010-08
期刊：
影响因子：
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通讯作者：
Alex Deibel;M. Valluri;D. Merritt
中科院分区：
文献类型：
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作者：
Alex Deibel;M. Valluri;D. Merritt
本文研究了一类中心超大质量黑洞的三轴势函数在旋转坐标系中的轨道族性质。在这样的星系中，大多数规则的盒子轨道（对维持三轴性至关重要）与占据配置空间中二维表面的共振有关。对于缓慢的图形旋转，所有的轨道族都很稳定。在中间模式速度的谐振盒轨道以及内部长轴管的显着部分是不稳定的“包络加倍”，从科里奥利力产生的，并被驱动到不稳定的中心。因此，对于2 × 108 yr <$Tp <$5 × 109 yr的图案旋转周期，两个对维持三轴性最重要的轨道族是高度混沌的。随着图案速度的增加，也有一个急剧下降的整体分数的短轴管和逆行品种相应的增加。在最高的模式速度（接近三轴杆），盒状轨道经历了一个突然的过渡到一个新的家庭的稳定逆行环状轨道，类似于三维酒吧的轨道，并围绕短轴循环。我们的分析意味着三轴系统（具有中央尖点和SMBH）可以像快速棒一样快速旋转，也可以像N体模拟中发现的三轴椭圆星系或暗物质晕一样缓慢旋转。保持稳定动力学平衡的无碰撞三轴系统不太可能具有中间模式速度，这在盒子和内部长轴管轨道家族中都产生高水平的随机性。
We survey the properties of all orbit families in the rotating frame of a family of realistic triaxial potentials with central supermassive black holes (SMBHs). In such galaxies, most regular box orbits (vital for maintaining triaxiality) are associated with resonances which occupy two-dimensional surfaces in configuration space. For slow figure rotation all orbit families are largely stable. At intermediate pattern speeds a significant fraction of the resonant box orbits as well as inner long-axis tubes are destabilized by the “envelope doubling” that arises from the Coriolis forces and are driven into the destabilizing center. Thus, for pattern rotation periods 2 × 108 yr ≲ Tp ≲ 5 × 109 yr, the two orbit families that are most important for maintaining triaxiality are highly chaotic. As pattern speed increases there is also a sharp decrease in the overall fraction of prograde short-axis tubes and a corresponding increase in the retrograde variety. At the highest pattern speeds (close to that of triaxial bars), box-like orbits undergo a sudden transition to a new family of stable retrograde loop-like orbits, which resemble orbits in three-dimensional bars, and circulate about the short axis. Our analysis implies that triaxial systems (with central cusps and SMBHs) could either be very rapidly rotating like fast bars or slowly rotating like triaxial elliptical galaxies or dark matter halos found in N-body simulations. Collisionless triaxial systems that remain in stable dynamical equilibrium are unlikely to have intermediate pattern speeds which produce a high level of stochasticity in both the box and inner long-axis tube orbit families.