论文标题
弱耦合方案中中子星芯中磁场演化的两流体模拟
Two-fluid simulations of the magnetic field evolution in neutron star cores in the weak-coupling regime
论文作者
论文摘要
在上一篇论文中，我们报道了通过双极扩散在中子星核中磁场演变的模拟，将中子作为一动不动的均匀背景。但是，在实际的中子星中，中子可以自由移动，强大的组成梯度会导致稳定的分层（针对对流运动的稳定性），这两者都可能影响进化的时标。在这里，我们通过提供由中子，质子和电子组成的中子芯组成的中子星核中轴向对称磁场演变的第一个长期两流体模拟，以解决这些问题。同样，我们发现磁场朝向压缩的“毕业生 - shafranov equilibria”，其中磁力通过带电颗粒的退化压力梯度和重力平衡。但是，由于中子的运动（与磁场偶联，但也受到中子施加的碰撞阻力限制），因此发现进化比一动不动的中子要快得多，因为中子现在可以移动。非轴对称不稳定性对这些平衡以及β衰减，质子超导性和中子超流体的可能影响留给了未来的工作。
In a previous paper, we reported simulations of the evolution of the magnetic field in neutron star cores through ambipolar diffusion, taking the neutrons as a motionless uniform background. However, in real neutron stars, neutrons are free to move, and a strong composition gradient leads to stable stratification (stability against convective motions) both of which might impact on the time-scales of evolution. Here we address these issues by providing the first long-term two-fluid simulations of the evolution of an axially symmetric magnetic field in a neutron star core composed of neutrons, protons, and electrons with density and composition gradients. Again, we find that the magnetic field evolves towards barotropic "Grad-Shafranov equilibria", in which the magnetic force is balanced by the degeneracy pressure gradient and gravitational force of the charged particles. However, the evolution is found to be faster than in the case of motionless neutrons, as the movement of charged particles (which are coupled to the magnetic field, but are also limited by the collisional drag forces exerted by neutrons) is less constrained, since neutrons are now allowed to move. The possible impact of non-axisymmetric instabilities on these equilibria, as well as beta decays, proton superconductivity, and neutron superfluidity, are left for future work.
