论文标题
新生中子星中的对流和发电机
Convection and Dynamo in Newly-born Neutron Stars
论文作者
论文摘要
为了研究原始恒星（PNSS）中磁流体动力学（MHD）对流和产生的发电机活性的性能，我们用解决可压缩的MHD方程与状态（EOS）（EOS）和简化的Leptonic运输构建了“盒子中的PNS”模拟模型。作为演示，我们将其应用于具有不同内部结构的两种类型的PNS模型：完全感染模型和球形壳对流模型。通过改变模型的自旋速率，研究了在PNS内部运行的对流和发电机的旋转依赖性。我们发现，由于旋转分层对流的湍流转运，在所有模型中都会开发出大规模的流量和热力学磁场。根据自旋速率和对流区的深度，获得了大规模结构的各种轮廓，可以将其物理理解为“平均场”运动方程的稳态解。除了那些流体动力结构外，在所有模型中，具有$ \ Mathcal {O}（O}（10^{15}）$ G的大型磁成分也自发地在无序的纠结磁场中组织。旋转速率越高，大规模磁成分的构建越强。有趣的是，作为总体趋势，完全感染的模型具有比球形壳对流模型的大型磁成分更强的大型磁成分。对流区域越深，对流涡流的大小就越大。结果，旋转约束的对流似乎更容易在完全处方的模型中实现，从而导致那里的大规模发电机的效率更高。为了更好地了解NS磁场多样性的起源，我们需要在更广泛的参数范围内研究PNS Dynamo。
To study properties of magneto-hydrodynamic (MHD) convection and resultant dynamo activities in proto-neutron stars (PNSs), we construct a "PNS in a box" simulation model with solving compressible MHD equation coupled with a nuclear equation of state (EOS) and a simplified leptonic transport. As a demonstration, we apply it to two types of PNS models with different internal structures: fully-convective model and spherical-shell convection model. By varying the spin rate of models, the rotational dependence of convection and dynamo that operate inside the PNS is investigated. We find that, as a consequence of turbulent transport by rotating stratified convection, large-scale structures of flow and thermodynamic fields are developed in all models. Depending on the spin rate and the convection zone depth, various profiles of the large-scale structures are obtained, which can be physically understood as steady-state solutions to the "mean-field" equation of motion. Additionally to those hydrodynamic structures, the large-scale magnetic component with $\mathcal{O}(10^{15})$ G is also spontaneously organized in disordered tangled magnetic fields in all models. The higher the spin rate, the stronger the large-scale magnetic component is built up. Intriguingly, as an overall trend, the fully-convective models have a stronger large-scale magnetic component than that in the spherical-shell convection models. The deeper the convection zone extends, the larger the size of the convection eddies becomes. As a result, the rotationally-constrained convection seems to be more easily achieved in the fully-convective model, resulting in the higher efficiency of the large-scale dynamo there. To gain a better understanding of the origin of the diversity of NS's magnetic field, we need to study the PNS dynamo in a wider parameter range.
