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Article Dans Une Revue Journal of Cosmology and Astroparticle Physics Année : 2008

On the determination of curvature and dynamical Dark Energy

Résumé

Constraining simultaneously the dark energy equation of state and the curvature of the universe is difficult due to strong degeneracies. To circumvent this problem when analyzing data it is quite usual to assume flatness to constrain dark energy, or conversely, to assume that dark energy is a cosmological constant to constrain curvature. Such assumptions may provide biases if they are not true. In this paper we quantify this question in view of the large amount of data which will be collected in the future. We simulate data for type Ia supernovae, the CMB shift parameter "$R$" and the so-called "$A$" parameter describing BAO with fiducial models having non-zero curvature and dynamical dark energy parametrized by an evolving equation of state : $w(a) = w_0 + (1-a) w_a$. By varying the curvature of the fiducial universe, we analyze the biases which can occur in the reconstruction of ($w_0,w_a$) when flatness is assumed. We find that models with curvature in the ranges $0.95<\Omega_T<0.99$ and 1.01<\Omega_T<1.08$ may induce a problematic misinterpretation of the data. We then study the regions of the ($w_0,w_a$) fiducial plane where one may confuse a flat cosmological constant model with a fiducial non-flat dynamical dark energy model. We find that with high statistics observations such confusions are seriously limited, and even impossible for closed models, but that biases on cosmological parameters may be important.

Dates et versions

hal-00263640 , version 1 (12-03-2008)

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J. -M. Virey, D. Talon-Esmieu, A. Ealet, P. Taxil, A. Tilquin. On the determination of curvature and dynamical Dark Energy. Journal of Cosmology and Astroparticle Physics, 2008, 12, pp.008. ⟨hal-00263640⟩
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