Abstract
In this article we investigate the properties of the FLRW flat cosmological models in which the cosmic expansion of the Universe is affected by a dilaton dark energy (Liouville scenario). In particular, we perform a detailed study of these models in the light of the latest cosmological data, which serves to illustrate the phenomenological viability of the new dark energy paradigm as a serious alternative to the traditional scalar field approaches. By performing a joint likelihood analysis of the recent supernovae type Ia data (SNIa), the differential ages of passively evolving galaxies, and the baryonic acoustic oscillations (BAOs) traced by the Sloan Digital Sky Survey (SDSS), we put tight constraints on the main cosmological parameters. Furthermore, we study the linear matter fluctuation field of the above Liouville cosmological models. In this framework, we compare the observed growth rate of clustering measured from the optical galaxies with those predicted by the current Liouville models. Performing various statistical tests we show that the Liouville cosmological model provides growth rates that match well with the observed growth rate. To further test the viability of the models under study, we use the Press–Schechter formalism to derive their expected redshift distribution of cluster-size halos that will be provided by future X-ray and Sunyaev–Zeldovich cluster surveys. We find that the Hubble flow differences between the Liouville and the LambdaCDM models provide a significantly different halo redshift distribution, suggesting that the models can be observationally distinguished.
Highlights
The comprehensive study carried out in recent years by the cosmologists has converged towards a cosmic expansion history that involves a spatially flat geometry and a recent accelerating expansion of the Universe
Performing a χ2 statistical test we show that the Liouville cosmological model provides growth rates that match sufficiently well with the observed growth rate
We find that the Hubble flow differences between the Liouville and the ΛCDM models provide a significantly different halo redshift distribution, suggesting that the models can be observationally distinguished
Summary
The comprehensive study carried out in recent years by the cosmologists has converged towards a cosmic expansion history that involves a spatially flat geometry and a recent accelerating expansion of the Universe (see [1,2,3,4,5,6,7,8] and references therein). In string theory, gauge and gravitational couplings are connected with the vacuum expectation value of scalar field called dilaton φ [26] In this context, it has been proposed by some of us a specific model for the DE. We note in passing that the presence of time dependent dilaton fields at late eras of the Universe, that characterizes Qcosmology, may lead to phenomenologically interesting extensions of minimal supergravity models The latter predict less dark-matter relic abundances than the conventional ΛCDM model, thereby allowing for more room for supersymmetry in collider (such as LHC) tests of the models [30, 34].
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