On Magnetohydrodynamic Jet Production in the Collapsing and Rotating Envelope
On Magnetohydrodynamic Jet Production in the Collapsing and Rotating Envelope
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折叠和旋转包络体中磁流体动力射流的产生
DOI：
10.1086/431276
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发表时间：
2005
期刊：
影响因子：
--
通讯作者：
D. Proga
中科院分区：
文献类型：
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作者：
D. Proga
我们目前的结果，从轴对称，时间相关的流体动力学（HD）和磁流体动力学（MHD）模拟的气体信封崩溃到黑洞（BH）。我们认为气体的角动量如此之小，在初始的瞬态后，在HD的情况下，流量直接吸积到BH上，而不形成旋转支撑的环面。然而，在MHD的情况下，即使初始磁场非常弱，气流也会形成四个分量的结构：（1）赤道流入，（2）双极流出，（3）极漏斗流出，（4）极漏斗流入。我们的分析集中在MHD流的第二流动分量上，这代表了一个简单而强大的例子，一个组织良好的流入/流出的MHD射流形成的问题的解决方案。喷流很重，高度磁化，由磁力和离心力驱动。喷流中总能量的很大一部分是由大规模磁场产生的。我们回顾以前的模拟，其中特定的角动量高于这里假设的，并得出结论，我们的双极外流发展为一个广泛的赤道附近和两极附近的流量的属性。未来的工作，这样一个简单的流入/流出的解决方案将有助于查明的关键要素的真实的射流/流出，以及帮助解释更复杂的模拟，旨在研究射流的形成和磁化信封的崩溃。
We present results from axisymmetric, time-dependent hydrodynamic (HD) and magnetohydrodynamic (MHD) simulations of a gaseous envelope collapsing onto a black hole (BH). We consider gas with such small angular momentum that, after an initial transient, the flow in the HD case accretes directly onto a BH without forming a rotationally supported torus. However, in the MHD case, even with a very weak initial magnetic field, the flow settles into a configuration with four components: (1) an equatorial inflow, (2) a bipolar outflow, (3) polar funnel outflow, and (4) polar funnel inflow. We focus our analysis on the second flow component of the MHD flow, which represents a simple yet robust example of a well-organized inflow/outflow solution to the problem of MHD jet formation. The jet is heavy, highly magnetized, and driven by magnetic and centrifugal forces. A significant fraction of the total energy in the jet is carried out by a large-scale magnetic field. We review previous simulations, in which specific angular momentum was higher than that assumed here, and conclude that our bipolar outflow develops for a wide range of the properties of the flow near the equator and near the poles. Future work on such a simple inflow/outflow solution will help to pinpoint the key elements of real jets/outflows as well as help to interpret much more complex simulations aimed at studying jet formation and the collapse of magnetized envelopes.