Cosmological dynamics of a nonminimally coupled scalar field system and its late time cosmic relevance

We investigate the cosmological dynamics of a nonminimally coupled scalar field system described by F()R coupling with F()=(1-ξN)R(N2) and the field potential V()=V 0n. We use a generic set of dynamical variables to bring out new asymptotic regimes of the underlying dynamics. However, our dynamical variables miss the most important fixed point-the deSitter solution. We make use of the original form of the system of equations to investigate the issues related to this important solution. In particular, we show that the deSitter solution which is a dynamical attractor of the system lies in the region of negative effective gravitational constant G N, thereby leading to a ghost-dominated universe in the future and a transient quintessence (phantom) phase with G N>0 around the present epoch. We also carry out a comparison of the model with other competing models of dark energy, such as Galileon-modified gravity and others. © 2012 American Physical Society.