Convective quenching of field reversals in accretion disc dynamos
Convective quenching of field reversals in accretion disc dynamos
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吸积盘发电机中场反转的对流淬灭
DOI：
10.1093/mnras/stx268
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发表时间：
2017
影响因子：
4.8
通讯作者：
Shigenobu Hirose
中科院分区：
文献类型：
--
作者：
Matthew S. B. Coleman;Evan Yerger;Omer Blaes;Greg Salvesen;Shigenobu Hirose
磁旋转湍流的垂直分层剪切盒模拟通常表现出所谓的准周期方位场反转的蝴蝶图。然而，在流体动力对流的存在下，场反转不再发生。相反，方位场强度准周期性地波动，同时保持相同的极性，其可以关于盘中平面对称或反对称。使用Hirose等人的模拟数据，我们证明了在存在对流的情况下场反转的缺乏是由于从更强磁化的上层到中平面的磁场的流体动力学混合，其然后消除从那里开始的场反转。我们的对流模拟在几个方面不同于其他人在以前的工作中报道的那些，其中较强的磁化可能起着比对流更重要的作用。
Vertically stratified shearing box simulations of magnetorotational turbulence commonly exhibit a so-called butterfly diagram of quasi-periodic azimuthal field reversals. However, in the presence of hydrodynamic convection, field reversals no longer occur. Instead, the azimuthal field strength fluctuates quasi-periodically while maintaining the same polarity, which can either be symmetric or antisymmetric about the disc mid-plane. Using data from the simulations of Hirose et al., we demonstrate that the lack of field reversals in the presence of convection is due to hydrodynamic mixing of magnetic field from the more strongly magnetized upper layers into the mid-plane, which then annihilate field reversals that are starting there. Our convective simulations differ in several respects from those reported in previous work by others, in which stronger magnetization likely plays a more important role than convection.