A bound system in the expanding universe with modified holographic Ricci dark energy and dark matter
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The evolution of a bound system in the expanding background has been investigated in this paper. The background is described by a FRW universe with the modified holographic dark energy model, whose equation of state parameter changes with time and can cross the phantom boundary. To study the evolution of the bound system, an interpolating metric is considered, and on this basis the geodesics of a test particle are given. The equation of motion and the effective potential are also derived from the geodesics. By studying the effective potential and the evolution of the radius of a test particle in the bound system of the Milky Way galaxy, we have found that the galaxy would go through three stages: expands from a singular point; stays in a discoid for a period of time; big rip in the future. With the help of analyzing the critical angular momentum, we find that the test particle needs less angular momentum to escape from the center mass as time passes.
KeywordsBound system Expanding background Modified holographic Ricci dark energy
This work was supported in part by the National Natural Science Foundation of China (Grants No. 11347101, No. 11405076), the Science Foundation of the Education Department of Yunnan Province (Grant No. 2014Y066), and the Talent Cultivation Foundation of Kunming University of Science and Technology (Grants No. KKSY201207053, No. KKSY201356060). Yu Zhang would like to acknowledge the support of the working Funds of the Introduced High-level Talents of Yunnan Province from the Department of Human Resources and Social Security of Yunnan Province.