吸积盘的线性二维MHD：晶体结构和能斯特系数
Linear Two-Dimensional MHD of Accretion Disks: Crystalline structure and Nernst coefficient
摘要：
我们分析了表征高磁化中子星上吸积盘稳态的二维MHD组态。我们描述的模型具有局部特征，代表了Coppi（2005）中概述的晶体结构的扩展，当考虑特定的吸积速率时，也处理局部模型。我们限制我们的注意力的线性化MHD制定的电磁反反应表征的平衡，通过固定的径向，垂直和方位角的配置文件的结构。由于我们只处理环形电流，模型的一致性是由一个小的碰撞效应的存在，现象学描述的非零常数能斯特系数（等离子体的热功率），以确保。这种效应通过与径向和垂直速度分量直接相关的非零温度梯度提供了电子力方程的适当平衡。我们表明，所获得的配置文件具有典型的振荡特征的晶体结构，调和与存在的粘度，相关的差分旋转的磁盘，并与净吸积率。事实上，我们提供了一个直接的关系之间的电磁反应的磁盘和（不再为零）增加其质量每单位时间。速度的径向吸积分量比赤道声速低几个数量级。它的类磁流体特征不允许真实物质进入中心物体（一种在非线性MHD修正中搜索的效应），但它解释了稳定通量的输出，有利于盘的环状形态。
英文摘要：
We analyse the two-dimensional MHD configurations characterising the steady state of the accretion disk on a highly magnetised neutron star. The model we describe has a local character and represents the extension of the crystalline structure outlined in Coppi (2005), dealing with a local model too, when a specific accretion rate is taken into account. We limit our attention to the linearised MHD formulation of the electromagnetic back-reaction characterising the equilibrium, by fixing the structure of the radial, vertical and azimuthal profiles. Since we deal with toroidal currents only, the consistency of the model is ensured by the presence of a small collisional effect, phenomenologically described by a non-zero constant Nernst coefficient (thermal power of the plasma). Such an effect provides a proper balance of the electron force equation via non zero temperature gradients, related directly to the radial and vertical velocity components. We show that the obtained profile has the typical oscillating feature of the crystalline structure, reconciled with the presence of viscosity, associated to the differential rotation of the disk, and with a net accretion rate. In fact, we provide a direct relation between the electromagnetic reaction of the disk and the (no longer zero) increasing of its mass per unit time. The radial accretion component of the velocity results to be few orders of magnitude below the equatorial sound velocity. Its oscillating-like character does not allow a real matter in-fall to the central object (an effect to be searched into non-linear MHD corrections), but it accounts for the out-coming of steady fluxes, favourable to the ring-like morphology of the disk.
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