Dissertation:Dynamics Analysis About Interactional Generalized Chaplygin Gas And The Fitting Of Parameters

Observations of Ia supernova indicates the expansion of the universe is ac-celerating.The accelerated universe implies the second order of scale factor a great than O.The right side of Einstein equation should contain a negative pressure part when taking Friedmann equation and the observations into con-sideration. This part is DE(dark energy).Reserach shows that quintessence field and cosmological constant can be candidates of DE.But the observa-tion discovered that dark matter and dark energy have the same order in current epoch,it lead to the coincidence problem" why are we living in an e-poch in which the density of dark energy and matter are comparable?"Many theories had been propounded to explain these problem;"tarcker fields",k-sessence,Chaplygin Gas,for example.These models can alleviates the coinci-dence problem and educe evolutive results which is independent of initial conditions.Furthermore,we can unify DM(dark matter) and DE when consid-ering the interaction between CG(Chaplygin gas) and DM.And we find the scale factor a close to zero at the early stage of universe,which means that the CG behave like DM.At the latter stage of universe,the state parameter ω close to-1,which means that the CG behave like DE.In this paper,we discussed four kinds of interaction between GCG and DM,they are Q=3βHptot,Q=βHρm,Q=3βHρmρ8/ρ8+ρm and Q=-3βHp8 (Where parame-ter β is dimensionless.ρm,ρ8 and ρtot are the density of matter, ChaplyginGas and the sum of both,respectively).We also have analyzed the properties of autonomous system and arrived some conclusions.