776 articles – 2954 Notices  [english version]
 HAL : hal-00019488, version 3
 arXiv : astro-ph/0602491
 Versions disponibles : v1 (22-02-2006) v2 (31-03-2006) v3 (26-05-2008)
 What can be learned about dark energy evolution?
 (22/02/2006)
 We examine constraints obtained from SNIa surveys on a two parameter model of dark energy in which the equation of state $w (z) = P(z) / \rho (z)$ undergoes a transition over a period significantly shorter than the Hubble time. We find that a transition between $w \sim -0.2$ and $w \sim -1$ (the first value being somewhat arbitrary) is allowed at redshifts as low as $0.1$, despite the fact that data extend beyond $z \sim 1$. Surveys with the precision anticipated for space experiments should allow only slight improvement on this constraint, as a transition occurring at a redshift as low as $\sim 0.17$ could still remain undistinguishable from a standard cosmological constant. The addition of a prior on the matter density $\Omega_\MAT = 0.3$ only modestly improves the constraints. Even deep space experiments would still fail to identify a rapid transition at a redshift above $0.5$. These results illustrate that a Hubble diagram of distant SNIa alone will not reveal the actual nature of dark energy at a redshift above $0.2$ and that only the local dynamics of the quintessence field can be infered from a SNIa Hubble diagram. Combinations, however, seem to be very efficient: we found that the combination of present day CMB data and SNIa already excludes a transition at redshifts below $0.8$.
 Domaine : Physique/Astrophysique/Cosmologie et astrophysique extra-galactiquePlanète et Univers/Astrophysique
 Mots Clés : Cosmology – Cosmic microwave background – Supernovae – Cosmological parameters
Liste des fichiers attachés à ce document :
 PS
 paper.ps(1.4 MB)
 PDF
 paper.pdf(301.8 KB)
 hal-00019488, version 3 http://hal.archives-ouvertes.fr/hal-00019488 oai:hal.archives-ouvertes.fr:hal-00019488 Contributeur : Marian Douspis <> Soumis le : Lundi 26 Mai 2008, 11:34:50 Dernière modification le : Lundi 26 Mai 2008, 11:38:07