论文标题
Galaxy流出的冷云发射。 iv。宇宙射线驱动的加速度
The Launching of Cold Clouds by Galaxy Outflows. IV. Cosmic-Ray-Driven Acceleration
论文作者
论文摘要
我们进行了一系列模拟宇宙射线（CR）驱动的，辐射冷却的冷云的演化，如银河流出中所示。在这种相互作用中，CRS以Alfvén速度向云流式传输，该速度在云边界处急剧下降，导致瓶颈压力在云端的前面累积。同时，CRS沿着云的侧面流，形成了一个大细丝的边界层。在此边界层中的剪切是云破坏的主要模式，在所有情况下，它相对较慢，但在AlfVén速度最低的情况下最慢。因此，瓶颈区域中的Cr射线压力有足够的时间有效地加速冷云。此外，辐射冷却对这些相互作用的影响相对较小。我们的模拟是二维的，并且受宇宙射线动力学的简化处理，CR加热的忽视和理想化的磁场几何形状的限制。然而，我们的结果表明，当充当动量输入的主要来源时，宇宙射线能够将云加速至速度，与在星系流出中观察到的速度相当。
We carry out a suite of simulations of the evolution of cosmic-ray (CR) driven, radiatively-cooled cold clouds embedded in hot material, as found in galactic outflows. In such interactions, CRs stream towards the cloud at the Alfvén speed, which decreases dramatically at the cloud boundary, leading to a bottleneck in which pressure builds up in front of the cloud. At the same time, CRs stream along the sides of the cloud, forming a boundary layer where large filaments develop. Shear in this boundary layer is the primary mode of cloud destruction, which is relatively slow in all cases, but slowest in the cases with the lowest Alfvén speeds. Thus the CR ray pressure in the bottleneck region has sufficient time to accelerate the cold clouds efficiently. Furthermore, radiative cooling has relatively little impact on these interactions. Our simulations are two-dimensional and limited by a simplified treatment of cosmic-ray dynamics, the neglect of CR heating, and an idealized magnetic field geometry. Nevertheless, our results suggest that cosmic rays, when acting as the primary source of momentum input, are capable of accelerating clouds to velocities comparable to those observed in galaxy outflows.
