Nonlinear Evolution of the Magnetorotational Instability in Eccentric Disks
Nonlinear Evolution of the Magnetorotational Instability in Eccentric Disks
复制标题
DOI：
10.3847/1538-4357/ac68f3
复制
发表时间：
2022-07-01
影响因子：
4.9
通讯作者：
Krolik, Julian H.
中科院分区：
文献类型：
--
作者：
Chan, Chi-Ho;Piran, Tsvi;Krolik, Julian H.
磁旋转不稳定性（MRI）已经在圆形磁化盘中得到了广泛的研究，它驱动吸积的能力已经在许多情况下得到了证明。有理由认为偏心磁化盘也存在，但MRI在这些磁盘中的行为仍然是未知的领域。在这里，我们提出的第一个模拟，按照非线性发展的MRI偏心磁盘。我们发现，在偏心磁盘的MRI类似于圆盘在两个方面，在整体水平的饱和度和详细的饱和状态的依赖磁拓扑结构。然而，与圆盘相反，偏心圆盘中的麦克斯韦应力在某些圆盘扇区中可以是负的，即使积分应力总是正的。角动量通量增加了圆盘内部的偏心率，减小了圆盘外部的偏心率。由于从偏心轨道吸积到黑洞上的物质比沿着最里面的稳定圆形轨道吸积的物质拥有更多的能量，偏心圆盘的辐射效率可能明显低于圆形圆盘。这可能解决在许多潮汐破坏事件中看到的“逆能量问题”。
The magnetorotational instability (MRI) has been extensively studied in circular magnetized disks, and its ability to drive accretion has been demonstrated in a multitude of scenarios. There are reasons to expect eccentric magnetized disks to also exist, but the behavior of the MRI in these disks remains largely uncharted territory. Here we present the first simulations that follow the nonlinear development of the MRI in eccentric disks. We find that the MRI in eccentric disks resembles circular disks in two ways, in the overall level of saturation and in the dependence of the detailed saturated state on magnetic topology. However, in contrast with circular disks, the Maxwell stress in eccentric disks can be negative in some disk sectors, even though the integrated stress is always positive. The angular momentum flux raises the eccentricity of the inner parts of the disk and diminishes the same of the outer parts. Because material accreting onto a black hole from an eccentric orbit possesses more energy than material tracing the innermost stable circular orbit, the radiative efficiency of eccentric disks may be significantly lower than circular disks. This may resolve the "inverse energy problem" seen in many tidal disruption events.