Magnetic Field Seeding by Galactic Winds
Magnetic Field Seeding by Galactic Winds
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DOI：
10.1111/j.1365-2966.2006.10474.x
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发表时间：
2006-04
影响因子：
4.8
通讯作者：
S. Bertone;C. Vogt;T. Ensslin
中科院分区：
文献类型：
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作者：
S. Bertone;C. Vogt;T. Ensslin
星系间磁场的起源仍然是一个谜，到目前为止已经提出了几种情景：其中包括原始相变、结构-形成激波和星系外流。在这项工作中，我们研究了银河系风如何有效地提供强烈而广泛的“种子”磁化。这可以用来解释今天在星系团和星际介质(IGM)中观察到的磁场。我们使用磁化星系风的半解析模拟与结构形成的高分辨率N体模拟相结合，来估计可以磁化到特定水平的IGM部分的下限和上限。我们发现，银河系的风能够使宇宙体积的很大一部分产生磁场。大多数受风影响的区域的磁场在10-12<；B<；10-8G的范围内，而更高的种子场只有在吹风的星系附近才能获得。这些种子磁场足够强，足以让一个中等效率的湍流发电机将它们放大到观测值。磁化区的体积填充系数强烈依赖于风从周围介质加载质量的效率。然而，风永远不会完全填满整个宇宙，即使在z=0时，也可以在宇宙空洞和不受反馈影响的区域找到原始气体。这意味着，原则上，可能有可能探测到这些区域中原始磁场的存在。
The origin of intergalactic magnetic fields is still a mystery and several scenarios have been proposed so far: among them, primordial phase transitions, structure-formation shocks and galactic outflows. In this work, we investigate how efficiently galactic winds can provide an intense and widespread 'seed' magnetization. This may be used to explain the magnetic fields observed today in clusters of galaxies and in the intergalactic medium (IGM). We use semi-analytic simulations of magnetized galactic winds coupled to high-resolution N-body simulations of structure formation to estimate lower and upper limits for the fraction of the IGM which can be magnetized up to a specified level. We find that galactic winds are able to seed a substantial fraction of the cosmic volume with magnetic fields. Most regions affected by winds have magnetic fields in the range 10 -12 < B < 10 -8 G, while higher seed fields can be obtained only rarely and in close proximity to wind-blowing galaxies. These seed fields are sufficiently intense for a moderately efficient turbulent dynamo to amplify them to the observed values. The volume-filling factor of the magnetized regions strongly depends on the efficiency of winds to load mass from the ambient medium. However, winds never completely fill the whole Universe and pristine gas can be found in cosmic voids and regions unaffected by feedback even at z = 0. This means that, in principle, there might be the possibility to probe the existence of primordial magnetic fields in such regions.