Theoretical Study On Interacting Dark Energy Models

At the end of the 20th century,a series of astronomical observations indicated that the universe was undergoing accelerated expansion.The possible explanation for the accelerated expansion is that the present universe is dominated by a strange component with negative pres-sure,this component is called as dark energy.Then,based on observations,the component proportion of the universe could be calculated,the Planck 2015 data tells us that,dark energy accounts for around 68.4 percent,dark matter accounts for around 26.7 percent,and baryonic matter accounts for just 4.9 percent.In order to further explore the relationship between dark energy and the accelerated expansion of the universe,various dark energy models have been proposed,such as the Quitessence,Phantom and other scalar dark energy models,series of Chaplygin gas as unified dark fluid models,interacting dark energy and dark matter models,etc.In this paper,we first briefly introduce the explanation of the accelerated expansion of the universe,and several kinds of dark energy models.Then,we analyze the interacting dark energy models from the cosmic background evolution,and study the evolutional law of density param-eters and deceleration parameters.By the analysis,we find that the early universe dominated by matter undergoes the decelerated expansion,the late universe dominated by dark energy under-goes the accelerated expansion,the interacting dark energy models could be adopted to explain the accelerated expansion of the universe.Besides,we employ the cosmological geometric di-agnosis to distinguish from the interacting dark energy models with different energy exchange forms.Based on the analysis of state finder hierarchy and Om geometric diagnostics,the S3(1)diagnosis shows the best effect when the coupling parameterξ is fixed and the equation of state parameter w is changed;meanwhile,with the invariable equation of state parameter w and variable coupling parameterξ,S4(1)would be the best diagnostic effect.Finally,we have done the stability analysis of the dynamic system to explore the stability of the interacting dark energy models,it is found that the dynamic system about two kind of interacting models own the attractor solutions,and the stability points can be used to explain that the present universe is undergoing accelerated expansion.