Abstract :
The implications of seven popular models of quintessence based on supergravity or M/string theory for the transition from a decelerating to an accelerating universe are explored. All seven potentials can mimic the ΛCDM model at low redshifts image. However, for a natural range of initial values of the quintessence field, the SUGRA and Polónyi potentials predict a transition redshift image for image, in agreement with the observational value image and in mild conflict with the ΛCDM value image. Tables are given for the quintessence potentials for the recent average image of the equation of state parameter, and for image and image in the low-z approximation image. It is argued that for the exponential potential image to produce a viable present-day cosmology, image. A robust, scaled numerical method is presented for simulating the cosmological evolution of the scalar field.
