ON THE DYNAMICS AND EVOLUTION OF GRAVITATIONAL INSTABILITY-DOMINATED DISKS
ON THE DYNAMICS AND EVOLUTION OF GRAVITATIONAL INSTABILITY-DOMINATED DISKS
复制标题
关于引力不稳定主导盘的动力学和演化
DOI：
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发表时间：
2010
期刊：
影响因子：
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通讯作者：
A. Burkert
中科院分区：
文献类型：
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作者：
M. Krumholz;A. Burkert
我们导出了描述一个由气体和恒星组成的轴对称薄盘的演化方程，该盘具有任意旋转曲线，由于吸积释放的能量和湍流衰变损失的能量之间的平衡，它保持在边缘引力不稳定和能量平衡状态。我们没有采用参数化的α公式，而是使用边缘引力不稳定的条件来自洽地确定位置和时间相关的输运率。我们表明，在引力不稳定性的支配下，磁盘有一个稳定的配置，即使考虑到恒星的形成，如果吸积率足够大，这种稳定状态仍然存在。对于处于这种状态的盘，我们分析确定了速度色散、表面密度、质量和角动量输运率作为气体质量分数、旋转曲线和盘边缘外部吸积率的函数。我们表明，最初脱离稳态的盘将在盘的粘性时间尺度上演变成稳态，这与吸积率高时的轨道周期相当。最后，我们讨论了这些结果在广泛的环境中对盘结构的影响，包括高红移星系、局部星系的外层气体盘和原恒星周围的吸积盘。
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 adopting a parameterized α 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.