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Abstract: The thawing quintessence model with a nearly flat potential provides anatural mechanism to produce an equation of state parameter, w, close to -1today. We examine the behavior of such models for the case in which thepotential satisfies the slow roll conditions: 1-VdV-dphi^2 << 1 and1-Vd^2 V-dphi^2 << 1, and we derive the analog of the slow-rollapproximation for the case in which both matter and a scalar field contributeto the density. We show that in this limit, all such models converge to aunique relation between 1+w, Omega phi, and the initial value of1-VdV-dphi. We derive this relation, and use it to determine thecorresponding expression for wa, which depends only on the present-day valuesfor w and Omega phi. For a variety of potentials, our limiting expression forwa is typically accurate to within delta w < 0.005 for w<-0.9. For redshift z< 1, wa is well-fit by the Chevallier-Polarski-Linder parametrization, inwhich wa is a linear function of a.

Autor: Robert J. Scherrer, A. A. Sen


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