Study On The Evolution Of Compact Star Binaries And Stellar X-ray Sources

X-ray is one of the most important bands in astronomy. It could be used to constrain the properties and the formation and evolution of X-ray emitting objects. X-ray can also be used to constrain the formation and evolution history of galaxies in the universe. As the launch of new instruments such as Chandra, XMM-Newton and Suzaku in recent years, we now can detect fainter X-ray sources, with more precise information of their location and spectra, which allows detailed study on their population, spatial distribution, and emission mechanism. In this thesis, we are going to discuss properties of point X-ray sources, especially those with white dwarfs as accretors. We focus on the evolution of these banaries and their progenitors, as well as the relation between these objects and their host environments. We further put constraints on the final product and the possible connection to type la supernovae.In the first chapter we give a brief introduction on both the observations and theo-ries of X-ray astronomy. We first review the observational properties of galactic bright X-ray sources, and then provide the theory of formation and evolution of compact X-ray binaries. We then discuss the properties of cataclysmic variables in different environ-ments in the Galaxy. We focus on the following topics:the common envelope evolu-tion, the accretion to compact stars, the unstable accretion disk, the interaction between the accreted matter and the compact star and the statistical study of cataclysmic vari-ables and the relation to their environments.In the second chapter we present the application of unstable accretion disk in the formation and evolution of GRO J1744-28and type la supernovae. We include the effect of unstable accretion disk to binary evolution code, and the latest description of H and He burning condition at the surface of white dwarfs to follow the evolution of white dwarf binaries with different initial masses and orbital periods. We also consider the products of white dwarfs with different initial mass after they accumulate enough matter. Our result shows that GRO J1744-28, the X-ray binary harboring a slow spin, high magnetic field neutron star and a low mass companion could have evolved from a binary with a normal star and an ONeMg WD as the accreter. During its evolution, the white dwarf experienced accretion from X-ray irradiated unstable accretion disk, then accumulated mass by burning the accreted matter on its surface before it collapses to a neutron star. The new formed neutron star then accrets from the companion again and evolves to its present properties. We also apply the unstable disk to the accretion of C/O white dwarfs and calculate the region of initial companion masses and orbital periods which could lead to successful type Ⅰa supernovae. The results suggest that the companion star of the progenitor system could have the initial mass as low as(?)1.5M⊙In the third chapter we present the calculation of the λ parameter, which was usu-ally taken as a fixed value in the common envelope evolution calculation. We adopt the latest binary stellar evolution code and include the effect of stellar wind and nuclear evolution to calculte the binding energy and λ parameters for both Pop. Ⅰ and Pop. Ⅱ stars. Our resuslts show that the λ parameter varies for stars with different initial masses. It also varies in different evolutional stages for the same star. At the end of their evolution, stars with initial mass between～3-6M⊙could have λ as large as several hundred. On the other hand, given similar initial mass and evolutional stage, Pop. Ⅰ stars always have higher λ than Pop. Ⅱ stars. The revised λ parameter could dramatically change the final products of common envelope evolution. We further fit the A for its further use in population synthesis.In chapter4We describe the statistical properties of faint X-ray sources in the Galactic bulge and globular clusters. We choose the’Limiting Window’in the bulge and four typical globular clusters in different dynamical stages to investigate the point sources detected from Chandra observations. We make corrections to the detection in-completeness and Eddington bias. We then remove interlopes statistically and build the luminosity functions of the point sources in these targets. We further calculate the specific number density of point sources in different luminosity ranges and make com-parisons between the bulge, the local field and the globular clusters. Our results show similarity between the luminosity function of the bulge and that of the local field. We confirm the flatness of the luminosity functions in the globular clusters. The globu-lar clusters seem to harbor more luminous X-ray sources and less faint ones. Our study gives quantitative correlation between the slope of the luminosity functions and the spe-cific dynamical encounter rates. Further investigation shows the source number density is also related to the location of the source in the cluster and the initial binary fraction of clusters. The results can be further used to constrain the initial and evolutional pa-rameters in stellar population synthesis work.We summarize and give prospects of future work in chapter5.