What makes the family of barred disc galaxies so rich: damping stellar bars in spinning haloes
What makes the family of barred disc galaxies so rich: damping stellar bars in spinning haloes
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是什么让棒盘星系家族如此丰富：旋转晕中的阻尼恒星棒
DOI：
10.1093/mnras/sty270
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发表时间：
2018
影响因子：
4.8
通讯作者：
Heller Clayton
中科院分区：
文献类型：
--
作者：
Collier Angela;Shlosman Isaac;Heller Clayton
我们模拟并分析了自旋暗物质（DM）晕中恒星棒的长期演化，其宇宙学自旋为λ ~ 0-0.09。利用高分辨率的恒星和DM数值模拟，我们重点研究了各种轴对称形状的恒星盘和DM晕之间的角动量交换——球形、扁圆形和长条形。我们发现，恒星棒经历了多样化的演化，这是由母晕吸收角动量J的能力所引导的，而角动量J是由圆盘通过引力力矩（共振和非共振）的作用而失去的。我们证实动力杆的不稳定性是通过共振j传递到光晕而加速的。我们的主要发现与盘晕系统的长期演化有关：随着λ的增加，棒状结构的增长较少，并且在通过垂直屈曲不稳定后基本溶解。具体地说，随着λ的增大，(1)恒星棒的垂直屈曲不稳定性与内晕吸收j的能力相互作用，这是削弱或破坏旋转晕棒的主要因素；(2)条形的j值逐渐减少，条形速度趋于平稳；(3)棒材更小，λ≤0.06时棒材在屈曲后完全停止生长；(4) λ > 0.03光晕中的棒子具有旋光与棒子半径之比RCR/Rb> 2，代表所谓的无偏移尘埃带的慢棒子。我们提供了盘晕系统中j传递的定量分析，并解释了快速旋转晕中没有增长的原因及其观测推论。我们得出的结论是，恒星条形结构的演变比预期的要复杂得多，条形结构也不像迄今为止认为的那样具有弹性。
We model and analyse the secular evolution of stellar bars in spinning dark matter (DM) haloes with the cosmological spin λ ∼ 0–0.09. Using high-resolution stellar and DM numerical simulations, we focus on angular momentum exchange between stellar discs and DM haloes of various axisymmetric shapes – spherical, oblate, and prolate. We find that stellar bars experience a diverse evolution that is guided by the ability of parent haloes to absorb angular momentum,J, lost by the disc through the action of gravitational torques, resonant and non-resonant. We confirm that dynamical bar instability is accelerated via resonantJ-transfer to the halo. Our main findings relate to the long-term secular evolution of disc–halo systems: with an increasing λ, bars experience less growth and basically dissolve after they pass through vertical buckling instability. Specifically, with increasing λ, (1) the vertical buckling instability in stellar bars colludes with inability of the inner halo to absorbJ– this emerges as the main factor weakening or destroying bars in spinning haloes; (2) bars lose progressively lessJ, and their pattern speeds level off; (3) bars are smaller, and for λ ≳ 0.06 cease their growth completely following buckling; (4) bars in λ > 0.03 haloes have ratio of corotation-to-bar radii,RCR/Rb> 2, and represent so-called slow bars without offset dust lanes. We provide a quantitative analysis ofJ-transfer in disc–halo systems, and explain the reasons for absence of growth in fast spinning haloes and its observational corollaries. We conclude that stellar bar evolution is substantially more complex than anticipated, and bars are not as resilient as has been considered so far.