A Research Of Jet Acceleration Mechanism For Low Luminosity Active Galactic Nuclei

This paper starts from the concept of AGN. Then we describe the observational characteristics, classification, central engine and disk-jet theory of AGN successively. Finally we induce the concept of LLAGN and elaborate the main features, central engine and RIAF-jet theory of LLAGN by contrast with AGN. Based on these theories, we explore the jet acceleration mechanism of low luminosity active galactic nuclei (LLAGNs) by analyzing theoretical models of accretion-jet and fitting observational data. The main work are as follows:Firstly, we propose a disk-corona model surrounding Kerr black hole in which the accretion disk is optically thick and geometrically thin. There exists a time-steady magnetic torque on the inner edge of disk. The analytical expressions for total gravitational power are derived by using thin-disk dynamics equations under the new boundary conditions. It shows such a torque can enhance the energy from disk corona to some extent. Furthermore, the global solution of the system is obtained, from which we find the ratio between power dissipated in the corona and that of total system increases with increasing BH spin parameter a*. However the ratio is insensitive to the additional radiation efficiency parameter Δε when Δε>1.Secondly, we explore the jet acceleration mechanism of disk-corona model. By solving the disk dynamics equations, the ratio of power dissipated in the corona to the total for disk-corona system is derived. Then the analytical expression of jet is obtained according to the electric circuit theory of the magnetosphere. The furthermore analyzing implies the power of jet increases with the increasing BH spin parameter a, and the majority of the power concentrates in the inner region of the disk-corona. Additionally, we use a sample consisting of 57 radio loud quasars to probe the jet production mechanism, which indicate that the disk-jet model can simulate almost all high-power jet source.Finally, we discuss the typical numerical solutions of ADAF and calculate the jet power of ADAF in the general relativity system by using the equivalent circuit method. Then the conclusion is obtained that the jet power concentrates in the inner region of the accretion flow and the more the component advection-dominated the lower the jet power of ADAF.