2004/07/19 by Steen Hannestad, Edvard Mörtsell, Edvard Mortsell · 2 citations
Earth and Planetary Sciences · Physics and Astronomy · #Astrophysics #Cosmic microwave background #Cosmological constant #Cosmology #Cosmology and Gravitation Theories #Dark energy #Equation of state #Galaxies: Formation, Evolution, Phenomena #Geophysics and Gravity Measurements #Mathematical physics #Parametrization (atmospheric modeling) #Physics #Quantum mechanics #Radiative transfer #Statistical physics #Supernova #Theoretical physics #astro-ph #hep-ph
paper · pdf · doi:10.1088/1475-7516/2004/09/001
published as JCAP 0409 (2004) 001 · 19 pages, 11 figures, JCAP format, typos corrected, references updated
arxiv created 2004/07/19 · openalex publication_date 2004/09/04 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
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 .