Neutron stars, and magnetars in particular, are known to host the strongest magnetic fields in the Universe. The origin of these strong fields is a matter of controversy. In this preliminary work, via numerical simulations, we study, for the first time in non-ideal general relativistic magnetohydrodynamic (GRMHD) regime, the growth of the magnetic field due to the action of the mean-field dynamo due to sub-scale, unresolved turbulence. The dynamo process, combined with the differential rotation of the (proto-)star, is able to produce an exponential growth of any initial magnetic seed field up to the values required to explain the observations. By varying the dynamo coefficient we obtain different growth rates. We find a quasi-linear dependence of the growth rates on the intensity of the dynamo. Furthermore, the time interval in which exponential growth occurs and the growth rates also seems to depend on the initial configuration of the magnetic field.

中文翻译：

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中子原恒星的广义相对论平均场发电机模型

众所周知，中子星，特别是磁星具有宇宙中最强的磁场。这些强大领域的起源是一个有争议的问题。在这项初步工作中，我们通过数值模拟首次研究了非理想的广义相对论磁流体动力学（GRMHD）体制中由于子尺度引起的平均场发电机的作用而引起的磁场的增长，未解决的湍流。发电机过程与（原）星的差速旋转相结合，能够产生任何初始磁场种子场的指数增长，直到解释观测所需要的值。通过改变发电机系数，我们可以获得不同的增长率。我们发现增长率对发电机强度的准线性依赖性。此外，