Some Studies On The Related Problems Of The Accelerated Expansion Of The Universe

The accelerating expansion of the Universe is one of the central problems of modern cosmology,after two separate research groups discovered astronomical phenomena in 1998,in which the expansion of the Universe was accelerating.General relativity does not explain this phenomena well,but it does allow the repulsive gravity to exist.At present,there are two main explanations for the accelerating expansion of the Universe.One is to modify the theory of gravitation,and the other one is dark energy.Recently,a new kind of f(z)theory is proposed to provide a different perspective for the development of reliable alternative models of gravity in which the f(R)Lagrangian terms are reformulated as polynomial parameterizations f(z).In the previous study,the parameters in the f(z)models have been constrained by using cosmological data.In this paper,these models will be tested by the observations in the solar system.After solving the Ricci scalar as a function of the redshift,one could obtain f(R)that could be used to calculate the standard Parameterized-Post-Newtonian(PPN)parameters.First,we fit the parametric models with the latest cosmological observational data.Then the tests are performed by solar system observations.And last we combine the constraints of solar system and cosmology together and reconstruct the f(R)actions of the f(z)parametric models.