等温线的径向扩展、分层、局部模型
Radially Extended, Stratified, Local Models of Isothermal Disks
摘要：
我们考虑等温吸积盘的局部分层数值模型。新的处理方法是径向范围L_x和方位范围L_y满足H << L_x，L_y << R，其中H是标度高度，R是局部半径。这使我们能够探测分层薄盘中的中尺度结构。我们在几个分辨率，大小和初始磁场强度的模型。与先前的工作一致，我们发现，饱和，湍流状态由一个弱磁化的磁盘中平面耦合到一个强磁化的日冕，在|z| ~ 2 H的过渡。饱和α~ 0.01 - 0.02。两点关联函数分析表明，盘中心4 H主要由小尺度湍流控制，统计上与非分层盘模型相似，而日冕磁场在~ 10 H尺度上是相关的。然而，通过日冕的角动量传输是很小的。对日冕中磁场环的研究表明，几乎没有开磁力线，主要是环形环，足点之间的特征距离为~ H。最后我们发现在磁场能量密度中存在特征时间尺度为~ 30 Ω^{-1}的准周期振荡。这些振荡与振荡的平均方位场，我们提出了一个唯象，α-发电机模型，捕捉大多数方面的振荡。
英文摘要：
We consider local, stratified, numerical models of isothermal accretion disks. The novel feature of our treatment is that radial extent L_x and azimuthal extent L_y satisfy H << L_x, L_y << R, where H is the scale height and R is the local radius. This enables us to probe mesoscale structure in stratified thin disks. We evolve the model at several resolutions, sizes, and initial magnetic field strengths. Consistent with earlier work, we find that the saturated, turbulent state consists of a weakly magnetized disk midplane coupled to a strongly magnetized corona, with a transition at |z| ~ 2H. The saturated α~ 0.01 - 0.02. A two-point correlation function analysis reveals that the central 4H of the disk is dominated by small scale turbulence that is statistically similar to unstratified disk models, while the coronal magnetic fields are correlated on scales ~ 10 H. Nevertheless angular momentum transport through the corona is small. A study of magnetic field loops in the corona reveals few open field lines and predominantly toroidal loops with a characteristic distance between footpoints that is ~ H. Finally we find quasi-periodic oscillations with characteristic timescale ~ 30 Ω^{-1} in the magnetic field energy density. These oscillations are correlated with oscillations in the mean azimuthal field; we present a phenomenological, alpha-dynamo model that captures most aspects of the oscillations.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
