Constraining super-critical string/brane cosmologies with astrophysical data

TL;DR

This paper evaluates unconventional dark energy models, including brane cosmologies and Liouville strings, against astrophysical data, finding they fit observations as well as LambdaCDM and suggest possible exotic dark matter behaviors.

Contribution

It introduces and tests alternative dark energy models based on brane cosmologies and Liouville strings, demonstrating their compatibility with observational data.

Findings

Evidence for negative-energy dust in current cosmology.

Detection of exotic scaling (a^{-4}) contributions to dark energy.

Q-cosmology models fit data as well as LambdaCDM across parameter ranges.

Abstract

We discuss fits of unconventional dark energy models to the available data from high-redshift supernovae, distant galaxies and baryon oscillations. The models are based either on brane cosmologies or on Liouville strings in which a relaxation dark energy is provided by a rolling dilaton field (Q-cosmology). Such cosmologies feature the possibility of effective four-dimensional negative-energy dust and/or exotic scaling of dark matter. We find evidence for a negative-energy dust at the current era, as well as for exotic-scaling (a^{-delta}) contributions to the energy density, with delta ~= 4, which could be due to dark matter coupling with the dilaton in Q-cosmology models. We conclude that Q-cosmology fits the data equally well with the LambdaCDM model for a range of parameters that are in general expected from theoretical considerations.