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High Energy Physical Processes in Active Galactic Nuclei

活动星系核中的高能物理过程

基本信息

批准号：
01540222
负责人：
TAKAHARA Fumio
金额：
$ 0.9万
依托单位：
Tokyo Metropolitan University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1989
资助国家：
日本
起止时间：
1989 至 1990
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-01540222/
关键词：
Accretion Disks Electron-Positron Pairs X-ray Background Radiation Mass Loss Active Galactic Nuclei Particle Acceleration Shock Waves Radio Galaxies 活動的銀河中心核相対論的プラズマ放射流体力学ジェット

项目摘要

1. We found that for two-temperature accretion disks with electron-positron pairs, there exists a critical accretion rate above which no steady state solutions exist. This conclusion proved to hold irrespective of whether soft photons are supplied by the cyclotron higher harmonics or external thermal photons. Dynamical behavior becomes important for higher accretion rates, which is left as a future problem.2. We investigated mass loss from accretion disks. If we give the shape of streamlines a priori, a singular point of the basic equation is shown to coincide with sonic point and the critical solution gives an appropriate solution of the wind. If we solve the shape of streamlines simultaneously under the assumption of self-similarity, singular point does not coincide with sonic point. Solutions which reach the infinity become supersonic without passing through the critical point if the density distribution in the disk is relatively flat. We started numerical study of disk winds and winds including electron-positron pairs.3. We examined models of the X-ray background in terms of a superposition of active galactic nuclei. To resolve the problem of spectral discrepancy we must incorporate either cosmological evolution of the spectral index or spectral flattening with energy for individual sources. Either model is shown to be successful if moderate luminosity evolution is assumed.4. We argued that shock waves in hot spots of radio galaxies can accelerate protons up to 10^<20>eV through the Fermi mechanism. We also found that for oblique shocks the efficiency of particle acceleration is enhanced up to 100 times compared with parallel shocks. Electron acceleration and its consequence on the observed properties of active galactic nuclei are interesting problems to be studied.

1. 我们发现，对于具有电子-正电子对的双温吸积盘，存在一个临界吸积速率，超过该临界吸积速率不存在稳态解。无论软光子是由高次谐波回旋加速器提供还是由外部热光子提供，这一结论都是成立的。动力学行为对更高的吸积率很重要，这是一个未来的问题。我们研究了吸积盘的质量损失。如果我们先验地给出流线的形状，则表明基本方程的奇异点与声速点重合，临界解给出了风的适当解。如果在自相似假设下同时求解流线的形状，奇点与声点不重合。如果圆盘内的密度分布相对平坦，则到达无穷大的解不经过临界点就变成超音速。我们开始了盘风和包括电子-正电子对在内的风的数值研究。我们根据活动星系核的叠加检验了x射线背景模型。为了解决光谱差异的问题，我们必须将光谱指数的宇宙演化或光谱平坦化与单个源的能量结合起来。如果假设中等亮度演化，两种模式都是成功的。我们认为射电星系热点的激波可以通过费米机制将质子加速到10^<20>eV。我们还发现，与平行激波相比，斜激波的粒子加速效率提高了100倍。电子加速及其对观测到的活动星系核性质的影响是值得研究的有趣问题。