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Numerical Simulations of Relativistic Jet Formation in Kerr Black Hole Magnetosphere

克尔黑洞磁层中相对论性喷流形成的数值模拟

基本信息

批准号：
13640235
负责人：
KOIDE Shinji
金额：
$ 1.98万
依托单位：
Toyama University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2001
资助国家：
日本
起止时间：
2001 至 2004
项目状态：
已结题

项目摘要

Relativistic jets from several kinds of objects in the universe have been found. It is believed that they are all formed by violent phenomena near the black holes. Among the proposed mechanisms, the magnetic mechanism of the jet formation is becaming most promising because it may explain not only the acceleration but also the collimation of the jets. However, the distinct mechanism has not yet been shown. To investigate the magnetic mechanism, we have developed the general relativistic magnetchydrodynamic (GRMHD) simulation code.First year of this research project, we have performed the GRMHD simulation of the rather simple system consisting of the Kerr black hole, rare uniform plasma, and the strong uniform magnetic field. The result dearly showed the strong power radiation from the black hole through the magnetic field. It also interestingly showed the magnetic mechanism of the energy extraction of the black hole. However, most of the plasma falls into the black hole and no jet is formed. Then, next we performed the GRMHD simulation of the cases with the radial magnetic field and the magnetic field induced by the electric current loop near the black hole. With these calculations, we have succeeded to show the relativistic outflow, whose velocity is larger than 90% of light speed. Especially, in the current loop magnetic field case, the magnetic flux tubes bridging the region between the ergosphere and the accretion disk around the black hole are twisted by the frame-dragging rapidly. The increase in the magnetic pressure in the magnetic tubes (magnetic bridge) causes the explosive expansion of the magnetic bridges. The numerical results show that the expansion produces the relativistic outflow. In conclusion, the magnetic bridge between the ergosphere and the accretion disk around the Kerr black hole never be steady-state and should be connected to the relativistic jets directly.

宇宙中有几种物体的相对论喷流已经被发现，人们认为它们都是由黑洞附近的剧烈现象形成的。在这些机制中，磁机制是最有前途的，因为它不仅可以解释射流的加速，而且还可以解释射流的准直。然而，独特的机制尚未显示。为了研究磁机制，我们开发了广义相对论磁流体动力学（GRMHD）模拟程序，在本研究项目的第一年，我们对由Kerr黑洞、稀有均匀等离子体和强均匀磁场组成的相当简单的系统进行了GRMHD模拟。结果清楚地显示了黑洞通过磁场的强能量辐射。它还有趣地展示了黑洞能量提取的磁性机制。然而，大部分等离子体福尔斯落入黑洞，没有喷流形成。然后，我们对黑洞附近的径向磁场和电流环感应磁场的情况进行了GRMHD模拟。通过这些计算，我们成功地显示了相对论外流，其速度大于光速的90%。特别是在电流环磁场情况下，连接能层和黑洞周围吸积盘之间的磁通量管被快速的标架拖曳扭曲。磁管（磁桥）中磁压力的增加导致磁桥的爆炸性膨胀。数值结果表明，膨胀产生了相对论外流。总之，Kerr黑洞周围能层与吸积盘之间的磁桥永远不会是稳态的，而应该直接与相对论喷流相连。