Shocks and angular momentum flips: a different path to feeding the nuclear regions of merging galaxies
Shocks and angular momentum flips: a different path to feeding the nuclear regions of merging galaxies
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DOI：
10.1093/mnras/stw2872
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发表时间：
2016-10
影响因子：
4.8
通讯作者：
Pedro R. Capelo;M. Dotti
中科院分区：
文献类型：
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作者：
Pedro R. Capelo;M. Dotti
我们研究星系合并的动力学，重点是核区域的气体喂养，使用一套星系相遇的流体动力学模拟。模拟的高空间和时间分辨率使我们不仅可以恢复潮汐扭矩引起的流入的标准图像，而且还可以详细描述由冲压压力产生的另一个重要的馈送路径。诱导激波有效地将气体的动力学与恒星的动力学解耦，极大地增加了气体角动量的损失，并导致中心流入增加。在许多情况下，撞击压力冲击也会导致较小星系的整个星系气体盘突然改变其旋转方向，导致一个完整的“翻转”，并在108年后随后发生“反翻转”。这一现象导致了长寿命解耦气体恒星和恒星-恒星盘的存在，这可能暗示了对一些观测到的运动学解耦核心/反旋转盘的起源的新解释。最后，我们推测，在非共面合并的情况下，可能存在一类新的残余系统，类似于一些观测到的x形射电星系。
We study the dynamics of galaxy mergers, with emphasis on the gas feeding of nuclear regions, using a suite of hydrodynamical simulations of galaxy encounters. The high spatial and temporal resolution of the simulations allows us to not only recover the standard picture of tidal-torque-induced inflows, but also to detail another, important feeding path produced by ram pressure. The induced shocks effectively decouple the dynamics of the gas from that of the stars, greatly enhancing the loss of gas angular momentum and leading to increased central inflows. The ram-pressure shocks also cause, in many cases, the entire galactic gas disc of the smaller galaxy to abruptly change its direction of rotation, causing a complete ‘flip’ and, several 108 yr later, a subsequent ‘counter-flip’. This phenomenon results in the existence of long-lived decoupled gas–stellar and stellar–stellar discs, which could hint at a new explanation for the origin of some of the observed kinematically decoupled cores/counter-rotating discs. Lastly, we speculate, in the case of non-coplanar mergers, on the possible existence of a new class of remnant systems similar to some of the observed X-shaped radio galaxies.