Year: 2004
Type: article
Abstract: We have calculated constraints on the evolution of the equation of state of the dark energy, w ( z ), from a joint analysis of data from the cosmic microwave background, large scale structure and type-Ia supernovae. In order to probe the time evolution of w we propose a new, simple parametrization of w , which has the advantage of being transparent and simple to extend to more parameters as better data become available. Furthermore it is well behaved in all asymptotic limits. Based on this parametrization we find that w ( z = 0) = −1.43 −0.38 +0.16 and d w /d z ( z = 0) = 1.0 −0.8 +1.0 . For a constant w we find that -1.34 ⩽ w ⩽ -0.79 at 95% CL. Thus, allowing for a time-varying w shifts the best fit present day value of w down. However, even though models with time variation in w yield a lower χ 2 than pure ΛCDM models, they do not have a better goodness-of-fit. Rank correlation tests on supernova data also do not show any need for a time-varying w .
Authors: Steen Hannestad, Edvard Mörtsell
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: bronze
Funder: CERN
OpenAlex ID: W1971604891