Cosmological parameter estimation using Very Small Array data out to ℓ =1500

Rafael Rebolo, Richard A. Battye, Pedro Carreira, Kieran Cleary, Rod D. Davies, Richard J. Davis, Clive Dickinson, Ricardo Genova-Santos, Keith Grainge, Carlos M. Gutiérrez, Yaser A. Hafez, Michael P. Hobson, Michael E. Jones, Rüdiger Kneissl, Katy Lancaster, Anthony Lasenby, J. P. Leahy, Klaus Maisinger, Guy G. Pooley, Nutan RajguruJosé Alberto Rubiño-Martin, Richard D E Saunders, Richard S. Savage, Anna Scaife, Paul F. Scott, Anže Slosar, Pedro Sosa Molina, Angela C. Taylor, David Titterington, Elizabeth Waldram, Robert A. Watson, Althea Wilkinson

    Research output: Contribution to journalArticlepeer-review


    We estimate cosmological parameters using data obtained by the Very Small Array (VSA) in its extended configuration, in conjunction with a variety of other cosmic microwave background (CMB) data and external priors. Within the flat A cold dark matter (ACDM) model, we find that the inclusion of high-resolution data from the VSA modifies the limits on the cosmological parameters as compared to those suggested by the Wilkinson Microwave Anisotropy Probe (WMAP) alone, while still remaining compatible with their estimates. We find that Ω bh 2 = 0.0234 -0.0014 +0.0012, Ω dmh 2 = 0.111 -0.016 +0.014, h = 0.73 -0.05 +0.09, n S = 0.97 -0.03 +0.06, 10 10A S = 23 -3 +7 and τ = 0.14 -0.07 +0.14 for WMAP and VSA when no external prior is included. On extending the model to include a running spectral index of density fluctuations, we find that the inclusion of VSA data leads to a negative running at a level of more than 95 per cent confidence (n run = -0.069 ± 0.032), something that is not significantly changed by the inclusion of a stringent prior on the Hubble constant. Inclusion of prior information from the 2dF galaxy redshift survey reduces the significance of the result by constraining the value of Ω m. We discuss the veracity of this result in the context of various systematic effects and also a broken spectral index model. We also constrain the fraction of neutrinos and find that f v <0.087 at 95 per cent confidence, which corresponds to m v <0.32 eV when all neutrino masses are equal. Finally, we consider the global best fit within a general cosmological model with 12 parameters and find consistency with other analyses available in the literature. The evidence for n run <0 is only marginal within this model.
    Original languageEnglish
    Pages (from-to)747-759
    Number of pages12
    JournalMonthly Notices of the Royal Astronomical Society
    Issue number3
    Publication statusPublished - 21 Sept 2004


    • Cosmic microwave background
    • Cosmology: observations


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