标题： 宇宙射线扩散效应下的磁旋转不稳定性分析 显示英文标题

标题： Analysis of the magneto-rotational instability with the effect of cosmic-ray diffusion

摘要： 我们展示了从磁流体动力学（MHD）的线性稳定性分析和2.5维模拟中获得的结果，这些结果涉及磁旋转不稳定性（MRI），包括宇宙射线（CRs）的影响。 我们考虑了沿磁场方向的CR扩散，但忽略了跨磁场线的扩散。 本文考虑了两种模型：剪切盒模型和不同旋转圆柱模型。 我们研究了MRI如何受到初始CR压力（即能量）分布的影响。 在剪切盒模型中，初始状态是均匀分布。 线性分析表明，MRI的增长率不依赖于CR扩散系数的值。 在不同旋转圆柱模型中，初始状态是一个由弱均匀垂直磁场穿过的常角动量多态盘。 线性分析表明，如果CR扩散系数较大，则MRI的增长率会更大。 这两个结果都通过MHD模拟得到了验证。 MHD模拟结果表明，MRI增长引起的物质向外运动不会受到CR压力梯度的阻碍，作用于集中物质的离心力变大。 因此，MRI的增长率增加。 另一方面，如果初始CR压力是均匀的，那么MRI的增长率几乎不依赖于CR扩散系数的值。 显示英文摘要

摘要： We present the results obtained from linear stability analysis and 2.5-dimensional magnetohydrodynamic (MHD) simulations of the magnetorotational instability (MRI), including the effects of cosmic rays (CRs). We took into account of the CR diffusion along the magnetic field but neglect the cross-field-line diffusion. Two models are considered in this paper: shearing box model and differentially rotating cylinder model. We studied how MRI is affected by the initial CR pressure (i.e., energy) distribution. In the shearing box model, the initial state is uniform distribution. Linear analysis shows that the growth rate of MRI does not depend on the value of CR diffusion coefficient. In the differentially rotating cylinder model, the initial state is a constant angular momentum polytropic disk threaded by weak uniform vertical magnetic field. Linear analysis shows that the growth rate of MRI becomes larger if the CR diffusion coefficient is larger. Both results are confirmed by MHD simulations. The MHD simulation results show that the outward movement of matter by the growth of MRI is not impeded by the CR pressure gradient, and the centrifugal force which acts to the concentrated matter becomes larger. Consequently, the growth rate of MRI is increased. On the other hand, if the initial CR pressure is uniform, then the growth rate of the MRI barely depends on the value of the CR diffusion coefficient.