Cosmological Parameters: Fashion and Facts - CNRS - Centre national de la recherche scientifique Accéder directement au contenu
Pré-Publication, Document De Travail Année : 2003

Cosmological Parameters: Fashion and Facts

Résumé

We are at a specific period of modern cosmology, during which the large increase of the amount of data leads to the idea that the determination of cosmological parameters has been achieved with a rather good precision. There is a large consensus around the so-called concordance model. Indeed this model does fit an impressive set of independent data: CMB $C_l$ curve, most current matter density estimations, Hubble constant estimation from HST, apparent acceleration of the Universe, good matching of the power spectrum of matter fluctuations. However, the necessary introduction of a non zero cosmological constant is an extraordinary new mystery for physics, or more exactly the come back of one of the ghost of modern physics since its introduction by Einstein. Here, I would like to emphasize that some results are established beyond reasonable doubt, like the (nearly) flatness of the universe and the existence of a dark non-baryonic component of the Universe. But also that the evidence for a cosmological constant may not be as strong as needed to be considered as established beyond doubt. In this respect, I will argue that an Einstein-De Sitter universe might still be a viable option. Three global tests: 1) the evolution of the abundance of clusters with redshift 2) the baryon fraction measured in local clusters 3) apparent evolution of the baryon fraction with redshift might be consistent with a high matter density for the Universe in the range $0.6-1.$. I therefore conclude that the dominance of vacuum to the various density contributions to the Universe is presently an interesting and fascinating possibility, but it is still premature to consider it as an established scientific fact (abridged).

Dates et versions

hal-00009538 , version 1 (04-10-2005)

Identifiants

Citer

A. Blanchard. Cosmological Parameters: Fashion and Facts. 2003. ⟨hal-00009538⟩
43 Consultations
0 Téléchargements

Altmetric

Partager

Gmail Facebook X LinkedIn More