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Dynamo Effects of Black Hole and Particle Acceleration

黑洞和粒子加速的发电机效应

基本信息

批准号：
10640257
负责人：
TOMIMATSU Akira
金额：
$ 0.58万
依托单位：
Nagoya University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1998
资助国家：
日本
起止时间：
1998 至 1999
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-10640257/
关键词：
High Energy Astrophysics Magnetized Fluids Black Hole Physics General Relatively

项目摘要

Black holes are interesting astrophysical objects which are final states if gravitional collapse if matter and work as sources of highly energetic phenomena found in recent observations. In particular, it is widely believed that supermassive black holes exist in the central region of active galactic nuclei, and plasma accreted by strong gravity forms a magnetosphere around the black-hole magnetosphere as an engine of the activity.1. First, using general relativistic magnetohydrodynamics,a rotating magnetosphere around a stationary black hole was investigated with the purpose of discussing the efficiently of dynamo action. It was shown that spinning motion of black hole is not so efficient to excite loop field lines against ohmic diffusion of magnetic fields. This is a clear answer for a controversial point among previous works. The alternative mechanism for self-excitation of magnetic fields due to charge separation in fluids was proposed, and it was found that flare-like activity becomes possible in the region where magnetized fluids have rotational motion with speeds nearly equal to the light velocity. This energy release of magnetic fields will be useful to produce plasma jet with highly relativistic speeds.2. Next, gravitational collapse to form a black hole in the magnetosphere was considered as a burst source of electromagnetic waves. Dynamical variation of gravitational fields can give a direct amplification of magnetic fields to generate wave emission. The characteristic burst pattern of gravitational collapse was found, which may allow us to check black hole formation in terms of observations of electromagnetic bursts. A detailed analysis for more realistic models of collapsing magnetized stars remains in future investigations.

黑洞是一种有趣的天体物理对象，它是物质引力坍缩的最终状态，也是最近观测中发现的高能现象的来源。特别是，人们普遍认为，超大质量黑洞存在于活动星系核的中心区域，强引力吸积的等离子体在黑洞磁层周围形成磁层，作为活动的引擎。首先，利用广义相对论磁流体力学对静止黑洞周围的旋转磁层进行了研究，目的是讨论发电机作用的有效性。结果表明，黑洞的自旋运动对磁场的欧姆扩散并不能有效地激发环场线。这是对以往作品中一个有争议的观点的明确回答。提出了流体中电荷分离引起磁场自激的另一种机制，并发现在磁化流体具有接近光速的旋转运动的区域可能出现耀斑活动。这种磁场的能量释放将有助于产生具有高度相对论速度的等离子体射流。其次，在磁层中形成黑洞的引力坍缩被认为是电磁波的爆发源。引力场的动态变化可以直接放大磁场以产生波发射。发现了引力坍缩的特征爆发模式，这可能使我们能够根据电磁爆发的观测来检查黑洞的形成。对更真实的磁化恒星坍缩模型的详细分析仍有待于未来的研究。