Generalized Chaplygin Cosmology With Changeable-signs Interactions

A large number of astronomical observations show that there exists a kind of re-pulsive energy which can not be observed directly, accounting for about73%of the energy of the universe. It is called dark energy. As one of dark energy models, the gen-eralized Chaplygin gas model has been widely discussed. But there exists coincidence problem in all dark energy models. And dark energy model with interactions can help to alleviate this problem. In this thesis, we study generalized Chaplygin gas model with sign-changeable interactions.In Chapter One, we mainly introduce observational foundations of modern cosmol-ogy and some accelerating universe models. Specially, dark energy models have been studied more widely. We discuss the problems existing in dark energy models, such as the coincidence problem. In order to alleviate the problem, dark energy model with interactions has been proposed.In Chapter Two, we elaborate the Chaplygin gas model、 generalized Chaplygin gas model and interacting generalized Chaplygin gas model.In Chapter Three, we introduce the knowledge of the dynamics system-the au-tonomous system and critical point. We also introduce the classification of critical point in linear system and the property of critical point in nonlinear system.In Chapter Four, we use the dynamical analysis method to explore the generalized Chaplygin gas model with the sign-changeable interactions. The solutions in the model can be completely classified.We also find some stable attractor solutions which can help to alleviate the coincidence problem and heteroclinic orbits. We use the numerical method to study the evolution of this model and find some different results. Especially, when the interaction has the form Q=3βqHρm,it becomes more and more weak and asymptotically close to zero at late time. So we can’t discover dark matter in observation, which consistents with the recent experimental results.In Chapter Five, we summarize our work in this thesis.