Dark Energy Constraints on Red-Shift-Based f(R) Gravity. (19th February 2013)

• Record Type: Journal Article
• Authors: Dabbaghchian, Setareh; Saffari, Reza
• Other Names: Kieda D. Academic Editor.; Zhao H. Academic Editor.
• Is Part Of: ISRN astronomy and astrophysics. Volume 2013(2013)
• Publication Date: 2013-02-19
• Subjects: Astronomy -- Periodicals; Astrophysics -- Periodicals; Astronomy; Astrophysics; Electronic journals; Periodicals; Electronic journals; 520
• DOI: 10.1155/2013/107325
• Languages: English
• ISSNs: 2090-4738

Abstract

Abstract : We have studied cosmological dynamics in f ( R ) gravity theory via cosmographic parameters. We have changed variables of field equations from time to red-shift and solved the achieved differential equation analytically for f ( R ) . Then we have used Taylor expansion to find general form of f ( R ) function around the present day value of scalar curvature. By introducing F ( z ) = d f ( R ) / d R we would simplify our calculations; if we consider F ( z ) as a given function we would restrict our answers of f ( R ) . In this paper we offer a linear form of F ( z ) = 1 + α z which leads us to a specific f ( R ) function, where α is a constant which depends on the present day value of deceleration parameter. As an example, using Taylor expansion coefficients, we have compared our analytically calculated function with reconstructed f ( R ) function for Dark Energy models. To reconstruct f ( R ) action for Dark Energy models, we have used corresponding H ( z ) of each Dark Energy model for calculating Taylor expansion coefficients. As our F ( z ) function is linear, the Taylor expansion coefficients would be a function of present day value of deceleration parameter.