Constraints on Dissipative Non-Equilibrium Dark Energy Models from Recent Supernova Data

Non-critical string cosmologies may be viewed as the analogue of off-equilibrium models arising within string theory as a result of a cosmically catastrophic event in the early Universe. Such models entail relaxing-to-zero dark energies provided by a rolling dilaton field at late times. We discuss fits of such non-critical models to high-redshift supernovae data, including the recent ones by HST and ESSENCE and compare the results with those of a conventional model with Cold Dark Matter and a cosmological constant and a model invoking super-horizon perturbations.