Cosmological constraints on the dark energy equation of state and its evolution
By S. Hannestad, E. Mortsell. 2004
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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 dw/dz(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 χ2 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.
Subfields: Astronomy and Astrophysics, Oceanography
View Paper: https://www.semanticscholar.org/paper/7a39e17e1eba34be54772b7befefcb427f6929d5
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Citations in the corpus
- Scrutinizing Exotic Cosmological Models Using ESSENCE Supernova Data Combined with Other Cosmological Probes (2007, background): “However, it is important to note that the time variation ofw can be parameterized in many ways (e.g., Hannestad & Mörtsell 2004; Barnes et al. 2005; Calvo & Maroto 2006; Huterer & Peiris 2006; Riess et al. 2007), and choosing a particular parameterization enforces a particular form of time…”