Galactic fountains as magnetic pumps
Galactic fountains as magnetic pumps
复制标题
作为磁力泵的银河喷泉
DOI：
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发表时间：
1995
期刊：
影响因子：
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通讯作者：
A. Shukurov
中科院分区：
文献类型：
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作者：
A. Brandenburg;D. Moss;A. Shukurov
我们研究了一个简单的星系喷泉的运动学模型，并证明了银河系平面上的水平场可以被泵入到几千秒差距的光晕中。这种泵送效应是由低层的拓扑结构造成的，其中上升气流（以热气体为代表）形成了一个连接的网络，而下降气流（与孤立的冷云相关）彼此断开。这样的涡流将大规模的磁场困在圆盘中，并将其沉积在喷泉涡流的顶部。与先前研究的拓扑泵模型不同，在我们的案例中，ow不局限于封闭的盒子，水平磁性ux可以从顶部泄漏出来。我们发现晕中有明显的平均磁场泵送，这可以用1{10 km s ?1阶的平流速度来参数化。由此产生的磁场强度在银河平面以上几千秒差距的高度（至少）与银河系底部的强度相当。
We study a simple, kinematical model of a galactic fountain ow and show that a horizontal eld in the galactic plane can be pumped into the halo to a height of several kiloparsecs. This pumping eeect results from the topological structure of the ow in which the updraughts (represented by hot gas) form a connected network, whereas the downdraughts (associated with isolated cool clouds) are disconnected from each other. Such a ow traps the large scale magnetic eld in the disc and deposits it at the top of the fountain ow. Unlike previously studied models of topological pumping, in our case the ow is not constrained to a closed box and horizontal magnetic ux can leak out at the top. We nd signiicant pumping of mean magnetic eld into the halo, that can be parameterised by an advection velocity of order 1{10 km s ?1. The resulting magnetic eld strength at a height of several kiloparsecs above the galactic plane is (at least) comparable with that at the base of the ow.