Emission Lines From And Images Of Relativistic Thick Or Warped Disks

Evidences accumulated in the past years that the radiative efficiency is high (10-30%)in Active Galactic Nuclei(AGN).The high efficiency is generally believed to be produced by releasing the binding energy of gas accretion onto supermassive black holes.The existence of black holes in nearby galactic nuclei is supported by the stellar and gaseous kinematics and is now widely accepted. The main focus has shifted from identifying such systems to characterizing and modeling the detailed properties of these systems.But the size of the system is so small,for a black hole of 10⁸M_?mass the size of event horizon is aboutγ～10^-5pc, beyond the capability of current observing facilities.Of course,the observation of rapid variability of continuum spectrum can give a upper limit of the emitter region,but the useful information in detail for emitter region is limited.Fortunately, nature has provided us with an extremely useful probe of this region-line spectrum diagnostic,such as broad iron Kαand Hαemission lines.The emission line spectrum produced by transitions between different energy levels of atom or ion is the main approach to study the emitter regions,and the solely method for black hole accretion disk.The equivalent width,asymmetry and net shift of the line profiles carry a lot of information of the emitter regions.The ratio of line flux can tell us the state of the emitter,and so.At present,the main work of such research is restricted to thin disk.According to accretion theory,the disk must become thick when the accretion rate is high,and the disk will be warped by external torques acted on it.The research for the influence of disk thickness and disk warping on the line profiles are very important both in theoretics and in observations.In this paper,we write a novel program to calculate this influence and make some comparison with observations,some meaningful results are obtained.This paper include four parts.In Chapter 1,we firstly introduce some basic knowledge of Kerr metric. Their properties and morphology are presented in detail,such as particle orbits, orthonormal tetrad etc.Following this is a brief review of the accretion physics of black hole.At last,we introduced the conception of reprocessing line emission.In Chapter 2,we present Fe Kαline profiles from and images of relativistic discs with finite thickness around a rotating black hole using a novel code.Previous studies have concentrated on the case of a thin,Keplerian accretion disc. This disc must become thicker and sub-Keplerian with increasing accretion rates. These can affect the line profiles and in turn can influence the estimation of the accretion disc and black hole parameters from the observed line profiles.A new disk model with finite thickness is presented.We write a novel code to calculate the line profiles with respect to different parameters.We find that the separation and the relative height between the blue and red peaks of the line profile diminish as the thickness of the disc increases.This code is also well-suited to produce accretion disc images.We calculate the redshift and flux images of the accretion disc and find that the observed image of the disc strongly depends on the inclination angle.The self-shadowing effect appears remarkable for a high inclination angle,and leads to the black hole shadow being completely hidden by the disc itself.In Chapter 3,we extend the numerical code described in previous chapter to deal with the warped discs.We compute the reprocessing emission line profiles from a warped relativistic accretion disc around a central black hole by including all relativistic effects.A parameterized disk model is used to obtain an insight into the impact of disc warping on the double-peaked Balmer emission line profiles. This model has the same number of free-parameters as an eccentric disk model. The disk divide into prograde and retrograde two cases which need not in thin Keplerian disk.We find that the ratio between the red and blue peaks of the line profiles cross unity can be naturally predicted by a twisted warp disk,and the warped disk model can reproduce a triplet-peaked line profile,or double peaked profile with additional plateaus in the line wing as observed in the SDSS spectra of some AGN.We show that disk warping can reproduce main features of multipeaked line profiles of four active galactic nuclei from the Sloan Digital Sky Survey. We also find the fraction of the radiation incident to the outer disc from the inner part can be enhanced by disc warping.This naturally solve the energy budget problem in circular Keplerian disk model.I summarize the main results and present some work which is being carried on in the last Chapter.