AI 中文总结
本研究利用DISCO数值模拟，探究厚环双星盘的偏心不稳定性与角动量转移机制，揭示盘厚度、黏滞对不稳定性增长及双星迁移方向反转的影响，完善了厚盘下双星-盘演化的物理图像。
AI 中文摘要
我们利用DISCO程序求解了带有等温热厚环双星盘（CBD）的等质量圆轨道受限双星的二维流体动力学方程。本研究探究了厚环双星盘的偏心不稳定性与角动量转移，以及二者对盘厚度和黏滞的依赖关系，研究重点针对马赫数满足$\mathcal{M}\leq 14$的更厚的厚环双星盘。我们将盘腔偏心率的增长率以及吸积过程的角动量输运作为双星-盘形态演化的诊断指标进行计算。厚环双星盘的力矩计算必须运行足够长的时间，才能让盘的偏心不稳定性达到饱和。一旦不稳定性饱和，作用在双星上的力矩会迅速反转符号，因此我们将偏心率饱和与双星的迁移行为反转联系起来：当盘处于演化状态时，双星向内迁移；而当盘偏心率达到饱和后，双星向外迁移。研究发现饱和时间与马赫数呈非线性相关，更厚的厚环双星盘需要更长的演化时间才能出现准稳态。当满足$\mathcal{M} \lesssim 5$时，偏心不稳定性不存在，因此迁移方向会反转，使得极厚的盘（满足$h/r \gtrsim 0.2$）会发生持续的向内迁移。本研究的结果与学界针对马赫数满足$\mathcal{M} \ge 10$的情况得到的结论一致。
英文摘要
Utilizing the DISCO code we solve the 2D hydrodynamic equations for an equal mass circular restricted binary with an isothermal circumbinary disk (CBD). This work explores the eccentric instability in the CBD and angular momentum transfer, and their dependence on disk thickness and viscosity. The focus is specifically on thicker CBDs, with Mach number, ($\mathcal{M}\leq 14$). The growth rate of the disk cavity's eccentricity and the angular momentum transport from accretion is calculated as diagnostics for binary-disk morphology evolution. Calculations of CBD torques must run long enough to allow saturation of the disk's eccentric instability. The torque on the binary rapidly flips sign once the instability saturates. Thus we connect eccentricity saturation to a reversal in migration behavior for the binary. The binary experiences inward migration while the disk is in an evolving state, and outward migration once the disk eccentricity has saturated. The saturation time was found to be non-linearly dependent on Mach number and thicker CBDs require longer evolution time for a quasi-steady state to appear. The eccentric instability is not present for $\mathcal{M} \lesssim 5$, and therefore migration reverses direction, leading to robustly inward migration for very thick disks $h/r \gtrsim 0.2$. The results of this work were found to be consistent with community results for Mach numbers $\mathcal{M} \ge 10$.
Comments7 pages, 4 figures, 1 table
