Reseach Of Gravitational Deflection Of Light In F(R) Gravity Theory And Restriction Of Cosmology Parameters By MCMC Methods

Large amounts of observational data indicate that the universe is in a state of acceleratingexpansion. The value of the deceleration factorq0and the dynamics reason of cosmicinflation is still not fully ascertained, There are two main methods which is used to limit thecurrent values of the cosmological parameters: one is to directly limit the parametersaccording to the kinematic model of the universal structure, the other is to limit cosmologicalparameters according to the combination of kinematic model and gravity model. In currentlythere are two kinds of gravity model that explain the dynamic reason for the acceleratingexpansion of the universe: one is dark energy model, the other is the f (R)gravity models.This paper is discuss the limit of the cosmology parameters’ values and the feasibility ofthe f (R)gravity theory. Firstly, we analyze the existing problems when using the kinematicmodel of structure of the universe to restrict cosmology parameter values. In case of lowredshift, the expansion formula of the distance and redshift relation can not accurately limitthe value of deceleration factorq0; in case of high redshift, the method of power series theexpansion of the distance and redshift relation about redshift z is not applicable for limitingcosmology parameters. so in case of low redshift, we make a series of processing to theobservation data of Ia supernova, and use fitting to the cosmology parameters; in case ofhigh redshift, we use variable substitution y1/1z, make expansion of the luminositydistance formula again, use fitting to the parameters. Secondly, we analyze problem of stateparameters in the dark energy model and the flatness problem. We discuss the feasibility thatthe f (R)gravity theory is used to limit cosmology parameters. According to galaxy rotationcurves we build up the f (R)gravity model, take this model to get the motion equation ofthe light and solve it to get the deflection angle of the light when it cross the sun’s edge,finally compare with the observational data and verify the reasonableness of the model.