Outflow Launching Mechanisms
Outflow Launching Mechanisms
复制标题
流出启动机制
DOI：
10.1007/s11214-013-0017-3
复制
发表时间：
2013
影响因子：
10.3
通讯作者：
S
中科院分区：
文献类型：
--
作者：
Ohsuga;K.;Mineshige;S
吸积流的流出似乎是吸积过程的普遍特征。众所周知，黑洞的吸积流有许多发射机制：热风、(连续体和线)辐射压力驱动风和磁力驱动风。要研究流出的物理过程，首先必须建立良好的底层吸积流模型。历史上，各种吸积盘模型都是在径向单区近似下建立的，但由于完全忽略了包括外流在内的气体在吸积流中的多维运动，因此它们不适合于探索外流机制。另一个限制来自于最重要的成分--圆盘粘度是由唯象的α-粘度模型描述的。在这里，我们不依赖于α粘性公式，而是基于全球二维辐射磁流体力学(Radiation MHD)模拟阐明吸积流和相关流出的理论。通过只控制一个参数，密度归一化，我们已经成功地产生了三种不同的吸积流状态，并证实了从所有三种吸积流状态：超临界状态、标准状态和低光度状态都发生了普遍的流出。特别是从超临界低光度吸积流中确认了较强的外流。发现了超临界(或超爱丁顿)吸积流的几个值得注意的特征，即相对论的准直流出流(喷流)和具有块状结构的低速非准直流出流。
Outflow from accretion flow seems to be quite general features of accretion processes. A number of launching mechanisms are known for accretion flow onto black holes: thermal wind, (continuum and line) radiation-pressure driven wind, and magnetically driven wind. To investigate the physics of outflow it is essential first to build good models for underlying accretion flow. Historically, various accretion disk models have been constructed under radially one-zone approximations, but they are not appropriate for exploring the outflow mechanisms, since the multi-dimensional motion of gas in accretion flow, including outflows, is totally neglected. Another limitation comes from that the disk viscosity, the most important ingredient, is described by the phenomenologicalα-viscosity model. We, here, elucidate the theory of accretion flow and associated outflow based on global, two-dimensional radiation-magnetohydrodynamic (radiation MHD) simulations, not relying on theα-viscosity prescription. We have succeeded in producing three distinct states of accretion flow by controlling only one parameter, a density normalization, and confirmed the occurrence of ubiquitous outflow from all the three states of accretion flow: supercritical, standard, and low-luminosity states. Especially strong outflow is confirmed from the supercritical and low-luminosity accretion flow. Several noteworthy features of the supercritical (or super-Eddington) accretion flows are found; that is, relativistic, collimated outflows (jets), and low-velocity, uncollimated outflows with clumpy structure.