A Theoretical Study Of The Accelerating Expansion Of Universe And The Variable Generalized Chaplygin Gas

The accelerating expansion of universe is one of the mostimportant problems for the research of contemporary physics and cos-mology. Observations of type Ia supernova in the end of last centuryleads to important opportunity for revealing new mystery of physics.Beginning with discussion on the in?ation of the universe at the veryearly times and the accelerated expansions of today respectively, thedefects of the standard hot big bang cosmology is discussed, and the-ories of in?ation as well as their complements to the standard modelis reviewed in this paper. Several ways to give rise to an accelera-tion expansion and several kinds of dark energy model are introducedin chapter 4. Also, the variable generalized Chaplygin gas (VGCG)model for describing the unification of dark energy and dark matteris proposed by us, which can include more general types of Chaplygingas. In addition, we plot the evolution of the deceleration parame-ter and the density parameters for various components and calculatethe corresponding values of the deceleration parameter q0, transitionredshift zT and the the current e?ective equations of stateω0(ed)e for dif-ferent values ofωde andα, which are consistent with astrodynamicsobservations. Finally, we diagnose the dark energy models using thestatefinder parameters.