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1 IAS - Institut d-astrophysique spatiale 2 LAPP - Laboratoire d-Annecy-le-Vieux de Physique des Particules 3 LATT - Laboratoire d-Astrophysique de l-Observatoire Midi-Pyrénées 4 IAP - Institut d-Astrophysique de Paris

Abstract : We examine constraints obtained from SNIa surveys on a two parameter model of dark energy in which the equation of state $w z = Pz - ho z$ 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 $0.8$.

Keywords : Cosmology Cosmic microwave background Supernovae Cosmological parameters





Autor: Marian Douspis - Yves Zolnierowski - Alain Blanchard - Alain Riazuelo -

Fuente: https://hal.archives-ouvertes.fr/



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