Superquintessence

Abstract

There is marginal evidence that the quintessential form of matter responsible for the acceleration of the universe observed today has ratio between pressure and energy density $w<-1$. Such a regime, called superacceleration, cannot be achieved with conventional scalar field models. The simplest non-exotic model achieving superacceleration is that of a scalar field nonminimally coupled to the Ricci curvature. This model is studied for general potentials and an exact superaccelerating solution is presented. In quintessential inflation, the model can have blue gravitational wave spectra, improving the prospects for the detection of cosmological gravitational waves.