Should we doubt the cosmological constant?
arXiv:1005.3655 · doi:10.1111/j.1365-2966.2010.17614.x
Abstract
While Bayesian model selection is a useful tool to discriminate between competing cosmological models, it only gives a relative rather than an absolute measure of how good a model is. Bayesian doubt introduces an unknown benchmark model against which the known models are compared, thereby obtaining an absolute measure of model performance in a Bayesian framework. We apply this new methodology to the problem of the dark energy equation of state, comparing an absolute upper bound on the Bayesian evidence for a presently unknown dark energy model against a collection of known models including a flat LambdaCDM scenario. We find a strong absolute upper bound to the Bayes factor B between the unknown model and LambdaCDM, giving B < 3. The posterior probability for doubt is found to be less than 6% (with a 1% prior doubt) while the probability for LambdaCDM rises from an initial 25% to just over 50% in light of the data. We conclude that LambdaCDM remains a sufficient phenomenological description of currently available observations and that there is little statistical room for model improvement.
10 pages, 2 figures
References in corpus (12)
- Five-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Likelihoods and Parameters from the WMAP data
- Improved Cosmological Constraints from New, Old and Combined Supernova Datasets
- Cosmological Constraints from the SDSS Luminous Red Galaxies
- Bayes in the sky: Bayesian inference and model selection in cosmology
- A Parameterized Post-Friedmann Framework for Modified Gravity
- Crossing the Phantom Divide with Parameterized Post-Friedmann Dark Energy
- Measuring the effective complexity of cosmological models
- On model selection forecasting, Dark Energy and modified gravity
- Parametrized Post-Friedmann Signatures of Acceleration in the CMB
- Present and future evidence for evolving dark energy
- Bayesian Calibrated Significance Levels Applied to the Spectral Tilt and Hemispherical Asymmetry
- Bayesian Evidence for a Cosmological Constant using new High-Redshift Supernovae Data