A Unified Model For Quasars And Microquasars And Its Application In Astrophysics

As is well known, quasars and microquasars are the objects of similar characteristics in astrophysics, belonging to two different scales. Both quasars and microquasars can be studied based on the theory of black hole (BH)accretion disk with large-scale magnetic fields, which has become an important field in astrophysics. In this paper, based on this theory, we discuss some individual and general characteristics in quasars and microquasars.In Chapter 1, we briefly introduce the astronomical observations of quasars and microquasars. And we review some correlations between quasars and microquasars.Chapters 2-5 are my own work on these two objects. In Chapter 2, we discuss the radio dichotomy in quasars. Based on the coexistence of the Blandford-Znajek (BZ)and magnetic coupling (MC)processes in BH accretion disk (hereafter BZMC model), we find that the observed dichotomy between radio-loud and radio-quiet quasars is well interpreted by the two parameters, the BH spin and the power-law index of the variation of the magnetic field on the disc. Furthermore, we discuss the correlation of jet powers with radio loudness of quasars in terms of these two parameters. It is found that the contours of radio loudness are approximately in accord with those of jet powers for several radio sources, implying roughly that the stronger jet power corresponds to stronger radio loudness.In Chapter 3 we give the explanation for the phenomenon of twin peak high frequency quasi-periodic oscillation ( HFQPO ) in microquasars, and discuss the correlations of jet with state transitions. We give an interpretation of the `jet line' in the hardness-intensity plane discussing the parameter space consisting of the BH spin and the power-law index for the variation of the large-scale magnetic field in the disk. Furthermore, we propose a new scenario for the spectral state transitions in microquasars based on fluctuation in densities of accreting plasma from a companion star.In Chapter 4, the correlations of quasars with microquasars are discussed based on some public characteristic in astronomical observation. The proportions of some quantities of the BH systems for both quasars and microquasars are derived by combining the observational data with BZMC. It is shown that the square of the magnetic field at the BH horizon is inversely proportional to the BH mass, while the accretion rate of the disk is proportional to the BH mass. In addition, the very steep emissivity indexes from the recent XMM-Newton observations of the nearby bright Seyfert 1 galaxy MCG-6-30-15 and the microquasars XTE J1650-500 are well fitted by considering the MC effects on the disk radiation. These results suggest strongly the correlations of quasars with microquasars.In Chapter 5, the other possible mechanisms of extracting energy from a rotating BH by magnetic field are discussed. These studies indicate that it is necessary to develop the theory of BH-accretion disk by combining different accretion mode with different mechanisms of energy extraction.In the last Chapter, we summarize the main results and point out some aspects to be improved in our future work.