Theoretical Study of Radio Galaxies

射电星系的理论研究

基本信息

批准号：
11640236
负责人：
TAKAHARA Fumio
金额：
$ 1.28万
依托单位：
Osaka University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1999
资助国家：
日本
起止时间：
1999 至 2000
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-11640236/
关键词：
Radio Galaxies Relativistic Jets Particle Acceleration Active Galactic Nuclei Gamma-Ray Astronomy X-Ray Astronomy Electron-Positron Pairs Relativistic Plasma

项目摘要

We have made theoretical investigations on the physical properties and bulk acceleration mechanism of relativistic jets in radio galaxies.1. We have solved the outflow of electron-positron pairs from hot accretion disks under the two-fluid and one-dimensional approximations. We have found that a major portion of the dissipated energy in the disk is converted to the internal and kinetic energies of pairs when the accretion rate is high, which confirms our previous result based on the one-zone approximation. This specific mechanism is the first successful one which connects gravitational energy release with jet formation.2. As for the bulk acceleration mechanism, we have investigated thermal acceleration of electron-positron pairs in a Wien equilibrium with photons at a relativistic temperature. We solved steady and spherically symmetric outflows and found that the terminal Lorentz factor easily reaches a few tens with a quite large efficiency. This mechanism is shown to naturally avoid previous difficulties of pair annihilation and radiation drag and thus proves to be very promising. The collimation problem remains to be open. This mechanism predicts strong MeV gamma-ray emission accompanying the jet formation, which can be checked by future observations.3. While a fair fraction of the energy of the relativistic jets is radiated in the internal shocks near the central engine, the remaining fraction is converted to the kinetic and internal energies of extended radio sources. We have examined the physical quantities such as magnetic field and relativistic electrons in the hot spots and lobes and found that they are compatible with our jet model consisting of mainly electron-positron pairs.

我们已经对射电星系中相对论喷气机的物理特性和批量加速机理进行了理论研究。1。我们已经解决了从两流体和一维近似下的热积聚磁盘中电子峰值对的流出。我们发现，当吸积率较高时，磁盘中耗散能量的主要部分被转换为对的内部和动能，这证实了我们先前基于单区近似值的结果。这种特定的机制是将重力释放与喷气形成联系起来的第一个成功的机制。2。至于批量加速机制，我们已经研究了在相对论温度下具有光子平衡中电子峰值对的热加速度。我们解决了稳定和球形对称流出的流出，发现末端洛伦兹因子很容易达到几十个，效率很高。这种机制自然会避免对成对an灭和辐射阻力的以前困难，因此被证明是非常有前途的。直接问题仍然待开。这种机制预测了伴随喷气组伴随的强大MEV伽马射线排放，可以通过未来的观察结果检查3。尽管相对论喷气机的能量的相当一部分在中央发动机附近的内部冲击中辐射出来，但剩余的部分将转换为扩展无线电源的动力学和内部能量。我们已经检查了热点和裂片中的物理量，例如磁场和相对论电子，发现它们与主要由电子 - 峰值对组成的喷气模型兼容。