Constraints on the Cardassian Expansion from the Cosmic Lens AllSky Survey Gravitational Lens Statistics
Abstract
The existence of a dark energy component has usually been invoked as the most plausible way to explain the recent observational results. However, it is also well known that effects arising from new physics (e.g., extra dimensions) can mimic the gravitational effects of a dark energy through a modification of the Friedmann equation. In this paper we investigate some observational consequences of a flat, matterdominated, and accelerating/decelerating scenario in which this modification is given by H^{2}=g(ρ_{m},n,q), where g(ρ_{m},n,q) is a new function of the energy density ρ_{m}, the socalled generalized Cardassian models. We mainly focus our attention on the constraints from the recent Cosmic AllSky Survey (CLASS) lensing sample on the parameters n and q that fully characterize the models. We show that, for a large interval of the qn parametric space, these models are in agreement with the current gravitational lenses data. The influence of these parameters on the acceleration redshift, i.e., the redshift at which the universe begins to accelerate, and on the age of the universe at highredshift is also discussed.
 Publication:

The Astrophysical Journal
 Pub Date:
 July 2005
 DOI:
 10.1086/430266
 arXiv:
 arXiv:astroph/0501026
 Bibcode:
 2005ApJ...627...26A
 Keywords:

 Cosmology: Cosmological Parameters;
 Cosmology: Observations;
 Cosmology: Gravitational Lensing;
 Cosmology: LargeScale Structure of Universe;
 Astrophysics
 EPrint:
 6 pages, 4 figures, AAS latex