Crossing the phantom divide without phantom matter

Abstract

A class of braneworld models can lead to phantom-like acceleration of the late universe, but without the need for any phantom matter. In the simplest models, the universe contains only cold dark matter and a cosmological constant. We generalize these models by introducing a quintessence field. The new feature in our models is that quintessence leads to a crossing of the phantom divide, w = −1. This is a purely gravitational effect, and there is no phantom instability. Furthermore, the Hubble parameter is always decreasing, and there is no big rip singularity in the future.

Crossing the phantom divide: theoretical implications and observational status

“…Thus, knowledge of Ω 0m and H(z) suffices to determine w(z) which is obtained from equation (1.5) as [23] w(z) = where f and g are appropriate functions determined by the modified gravity theory [24,25,26,27,28,29]. In this class of models, the parameter w(z) can also be defined from equation (1.6) but it can not be interpreted as pX ρX of a perfect fluid.…”

A Braneworld Dark Energy Model with Induced Gravity and the Gauss-Bonnet Effect

“…Quintessential scheme can also be achieved in a geometrical way in higher order theories of gravity [10]( see also [4]). Phantom-like behavior without phantom matter [8] and also phantom-like behavior in a brane-world setup with induced gravity and curvature effects have been reported [11].…”

Cosmological constraints combiningH(z), CMB shift and SNIa observational data

“…The various approaches to confronting models with data are based on deriving the luminosity distance D L (z) [24], w de (z) [17,18,25,26] or H(z) [15,16,19,27,28].…”