How many dark energy parameters

By Eric Linder, D. Huterer. 2005

138 citations recorded by the source corpus.

For exploring the physics behind the accelerating universe a crucial question is how much we can learn about the dynamics through next generation cosmological experiments. For example, in defining the dark energy behavior through an effective equation of state, how many parameters can we realistically expect to tightly constrain? Through both general and specific examples (including new parametrizations and principal component analysis) we argue that the answer is 42 - no, wait, two. Cosmological parameter analyses involving a measure of the equation of state value at some epoch (e.g., w_0) and a measure of the change in equation of state (e.g., w') are therefore realistic in projecting dark energy parameter constraints. More elaborate parametrizations could have some uses (e.g., testing for bias or comparison with model features), but do not lead to accurately measured dark energy parameters.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/583b2191c37fc2bd0da960a68497396f14fa43c5

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Citations in the corpus

The dynamics of quintessence, the quintessence of dynamics (2007, background): “One could continue developing more complicated forms but sadly even the next generation of experiments will not be able to constrain stringently more than two equation of state parameters (Linder & Huterer, 2005).”
DESI 2024: reconstructing dark energy using crossing statistics with DESI DR1 BAO data (2024, methodology): “While the expansion in w ( z ) requires only 2 free parameters for the best-fit χ 2 to “converge” (as known from the success of w 0 – w a [see also 116]), the expansion of f DE ( z ) requires at least 3 free parameters to achieve similar performance.”
Observational probes of cosmic acceleration (2012, background): “The PCA approach has the advantage of allowing quite general w(z) histories to be represented, though in practice only a few PCs can be constrained well; Linder and Huterer (2005) and de Putter and Linder (2008) have argued that the w0 −wa parameterization has equal power for practical purposes.”
Scrutinizing Exotic Cosmological Models Using ESSENCE Supernova Data Combined with Other Cosmological Probes (2007, methodology): “Promising nonparametric techniques include a type of principal component analysis that allows the reconstruction of cosmological fetures such asρ(z), w(z), and their derivatives, as a function of redshift (e.g., Linder & Huterer 2005; Huterer & Cooray 2005; Huterer & Peiris 2006; Riess et al. 2007).”