Article

# The CODEX-ESPRESSO experiment: cosmic dynamics, fundamental physics, planets and much more..

12/2007; DOI: 10.1393/ncb/i2008-10514-x

Source: arXiv

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**ABSTRACT:**We study the general properties of attractors in a cosmological model with tachyonic potential and a scalar field nonminimally coupled to matter. In the conventional approach to the stability analysis the qualitative properties of the equations and of the long-term behavior of the solutions are investigated where the scaling solutions are the late time attractors and independent of the initial conditions. In this article, in a new approach, we examine the stability analysis of the model by simultaneously solving the dynamical system and best fitting the stability parameters with the observational data. The advantage of this approach is that the model which was of a purely mathematical nature become physically motivated. The number of the new critical points and also their properties, given in terms of the best-fitted parameters, may alter due to the best-fitting procedure. In a further step in stability analysis, we best fit both the stability parameters and initial conditions with the observational data. The results impose more constraints on the trajectories in the phase space and provide more information about the dynamics of the cosmological model.Physical review D: Particles and fields 01/2011; 83. - [Show abstract] [Hide abstract]

**ABSTRACT:**We study the redshift drift, i.e., the time derivative of the cosmological redshift in the Lemaître-Tolman-Bondi (LTB) solution in which the observer is assumed to be located at the symmetry center. This solution has often been studied as an anti-Copernican universe model to explain the acceleration of cosmic volume expansion without introducing the concept of dark energy. One of the decisive differences between LTB universe models and Copernican universe models with dark energy is believed to be the redshift drift. The redshift drift is negative in all known LTB universe models, whereas it is positive in the redshift domain z≲2 in Copernican models with dark energy. However, there have been no detailed studies on this subject. In the present paper, we prove that the redshift drift of an off-center source is always negative in the case of LTB void models. We also show that the redshift drift can be positive with an extremely large hump-type inhomogeneity. Our results suggest that we can determine whether we live near the center of a large void without dark energy by observing the redshift drift.Physical review D: Particles and fields 02/2011; 83(4). - [Show abstract] [Hide abstract]

**ABSTRACT:**In this paper we consider FRW cosmology in $F(R)$ modified gravity. It is shown that in particular cases the bouncing solution may appears in the model whereas the equation of state (EoS) parameter may crosses the phantom divider. For the dynamical universe, quantitatively we also find parameters in the model which satisfies two independent tests:the model independent Cosmological Redshift Drift (CRD) test and the type Ia supernova luminosity distances.

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