Theoretical Study of Time Dependent Radiative Transfer in Relativistic Astrophysical Plasmas

我研究了类星体和活动星系核中大质量黑洞附近产生的相对论等离子体的性质。我开发的数值代码，处理时间相关的辐射传输与康普顿散射和电子-正电子对的生产。我研究了瞬时加热等离子体的时间发展，发现质子的初始热能在大约10倍于初始汤姆逊时间的时间尺度上转移到电子和光子，其中大约20%用于对的产生。研究了等离子体云的稳态结构，得到了质子温度、电子温度、电子对浓度和光子谱的空间分布。在中心区域的温度较低，对浓度高于均匀模型预测相同的加热速率。由于光子的各向异性分布，对大气的影响较小，将结果应用于双温吸积盘，考虑了正负电子对的影响。我发现，固定的解决方案没有实现高吸积率，因为对平衡没有建立预期范围内的电子温度和汤姆逊深度。当轫致辐射或回旋高次谐波康普顿化主导辐射过程时，临界吸积率仅相当于爱丁顿光度的百分之几，这一结果提出了高吸积率双温吸积盘的行为问题.我以一种简化的方式研究了流体动力风从热盘吹出的一种可能性，并发现一种重要的物质可以通过风而丢失。将继续进行更全面的调查。

I investigated the properties of relativistic plasmas which are produced near massive black holes in quasars and active galactic nuclei. I developed the numerical code which treats time dependent radiative transfer with Compton scattering and electron-positron pair production. I studied the time development of the instantaneously heated plasmas and found that the initial thermal energy of protons is transferred to electrons and photons on the time scale of about 10 times the initial Thomson time and about 20 percent of it is used for pair production. I also studied the stationary structure of plasma clouds and obtained the spatial distribution of proton and electron temperatures, pair concentration and photon spectra. In the central region the temperatures are lower and the pair concentration is higher than the uniform model predicts for the same heating rate. Pair atmosphere is less de veloped because of the anisotropic distribution of photons.The results are applied to the two-temperature accretion disks, taking account of the effects of electron-positron pairs. I found that stationary solutions are not realized for high accretion rates because pair equilibrium is not established for the expected range of electron temperature and Thomson depth. The critical accretion rate corresponds to only a few percent of the Eddington luminosity when either bremsstrahlung or the Comptonization of cyclotron higher harmonics dominates the radiation process.This result raises the problem of the behavior of the two-temperature accretion disks for high accretion rates. I examined one possibility of hydrodynamical wind blowing from hot disks in a simplified way and dound that a significant matter can be lost through the wind. A fuller investigation will be continued.