Accretion disks in black hole X-ray binary systems.

摘要

Black hole X-ray binary systems are a main class of X-ray binaries, in which the matter torn from the surface of the companion by the compact object's (black hole in this case) gravitational field forms an accretion disk around the compact object. This accretion process provides the fuel for the observed X-ray emission and also makes the black hole X-ray binaries the natural laboratories for studying the physics in strong gravitational fields.; In this dissertation, I focus my attention on the continuum spectra of the black hole X-ray binaries. We first develop a radiative transfer correction procedure for recovering the original accretion disk flux, in order to refer the inner accretion disk radius. We then use the Monte-Carlo technique to simulate the inverse Compton scattering and to establish the physical connection between low energy photons and high energy photons detected in these binaries; several physically consistent table models are built in the XSPEC package for estimating the physical parameters of the disk-corona system via X-ray spectral model fitting. We further use the Monte-Carlo technique to study the accretion disk structure in the Cygnus X-1 system. Finally we propose a new method for utilizing Chandra data to study the distortion to the source spectrum induced by the X-ray scattering halo results from the interstellar medium.; We conclude that (1) the inner disk radius for a black hole X-ray binary keeps a stable value when the source transits between the high/soft spectral state and the low/hard state, and the substantial variation reported by the previous work is due to the negligence of spectral distinction and flux reduction of the observed disk emission by the inverse Compton scattering in the corona; the constant inner disk radius we derived suggests that the inner disk radius might be the radius of the marginally stable circular orbit of the central black hole; (2) the accretion disk in the Cygnus X-1 system has an additional warm layer between the cold disk, and the hot corona and the electron density distribution in the warm layer is non-uniform; (3) the X-ray scattering halo spectrum is much softer than the point source spectrum, which would induce some distortion to the point source spectrum.