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，对于具有正负电子对的双温吸积盘，存在一个临界吸积速率，高于该速率则不存在稳态解。事实证明，无论软光子是由回旋加速器高次谐波还是外部热光子提供，这一结论都成立。动态行为对于更高的吸积率变得很重要，这将成为未来的问题。2．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，则基本方程的奇点与声速点一致，并且临界解给出了风的适当解。如果在自相似的假设下同时求解流线形状，则奇异点与声速点不重合。如果圆盘中的密度分布相对平坦，则达到无穷远的溶液会变成超音速，而不会通过临界点。我们开始了盘状风和包含正负电子对的风的数值研究。 3．我们根据活动星系核的叠加研究了 X 射线背景模型。为了解决光谱差异问题，我们必须将光谱指数的宇宙演化或光谱平坦化与单个光源的能量结合起来。如果假设适度的光度演化，则这两种模型都被证明是成功的。4．我们认为射电星系热点中的冲击波可以通过费米机制将质子加速到10^20eV。我们还发现，对于斜向激波，粒子加速效率比平行激波提高了 100 倍。电子加速及其对活动星系核观测特性的影响是需要研究的有趣问题。