Bayesian model selection analysis of WMAP3

Parkinson, David, Mukherjee, Pia and Liddle, Andrew R (2006) Bayesian model selection analysis of WMAP3. Physical Review D, 73 (12). pp. 1235231-1235237. ISSN 0556-2821

PDF - Published Version
Download (204kB) | Preview


We present a Bayesian model selection analysis of WMAP3 data using our code CosmoNest. We focus on the density perturbation spectral index nS and the tensor-to-scalar ratio r, which define the plane of slow-roll inflationary models. We find that while the Bayesian evidence supports the conclusion that nS≠1, the data are not yet powerful enough to do so at a strong or decisive level. If tensors are assumed absent, the current odds are approximately 8 to 1 in favor of nS≠1 under our assumptions, when WMAP3 data is used together with external data sets. WMAP3 data on its own is unable to distinguish between the two models. Further, inclusion of r as a parameter weakens the conclusion against the Harrison–Zel’dovich case (nS=1, r=0), albeit in a prior-dependent way. In appendices we describe the CosmoNest code in detail, noting its ability to supply posterior samples as well as to accurately compute the Bayesian evidence. We make a first public release of CosmoNest, now available at

Item Type: Article
Schools and Departments: School of Mathematical and Physical Sciences > Physics and Astronomy
Depositing User: David Parkinson
Date Deposited: 06 Feb 2012 20:55
Last Modified: 06 Aug 2019 12:45

View download statistics for this item

📧 Request an update