引力不稳定性主导的混沌系统的动力学和演化
On the Dynamics and Evolution of Gravitational Instability-Dominated Disks
摘要：
我们推导出描述一个薄的轴对称盘的气体和恒星的任意旋转曲线，保持在一个边缘的引力不稳定性和能量平衡的状态，由于吸积释放的能量和能量之间的平衡，由于湍流衰减损失的演化方程。而不是采用参数化的α处方，而是使用的条件的边缘引力不稳定性，自洽地确定的位置和时间相关的传输率。我们表明，有一个稳定状态的配置占主导地位的磁盘引力不稳定性，这种稳定状态持续存在，即使当恒星形成考虑到如果吸积率是足够大的。对于在这种状态下的磁盘，我们分析确定的速度色散，表面密度，质量和角动量传输率作为气体质量分数的函数，旋转曲线，和外部吸积到磁盘边缘的速度。我们表明，磁盘最初脱离稳定状态将演变成它的粘性时标的磁盘，这是可比的轨道周期，如果吸积率高。最后，我们讨论了这些结果的影响，在广泛的环境中，包括高红移星系，外气体盘的本地星系，和吸积盘周围的原恒星的磁盘结构。
英文摘要：
We derive the evolution equations describing a thin axisymmetric disk of gas and stars with an arbitrary rotation curve that is kept in a state of marginal gravitational instability and energy equilibrium due to the balance between energy released by accretion and energy lost due to decay of turbulence. Rather than adopt a parameterized alpha prescription, we instead use the condition of marginal gravitational instability to self-consistently determine the position- and time-dependent transport rates. We show that there is a steady-state configuration for disks dominated by gravitational instability, and that this steady state persists even when star formation is taken into account if the accretion rate is sufficiently large. For disks in this state we analytically determine the velocity dispersion, surface density, and rates of mass and angular momentum transport as a function of the gas mass fraction, the rotation curve, and the rate of external accretion onto the disk edge. We show that disks that are initially out of steady state will evolve into it on the viscous timescale of the disk, which is comparable to the orbital period if the accretion rate is high. Finally, we discuss the implications of these results for the structure of disks in a broad range of environments, including high redshift galaxies, the outer gaseous disks of local galaxies, and accretion disks around protostars.
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