A preference for a non-zero neutrino mass from cosmological data

S. W. Allen, R. W. Schmidt, S. L. Bridle

    Research output: Contribution to journalArticlepeer-review

    Abstract

    We present results from the analysis of cosmic microwave background (CMB), large-scale structure (galaxy redshift survey) and X-ray galaxy cluster (baryon fraction and X-ray luminosity function) data, assuming a geometrically flat cosmological model and allowing for tensor components and a non-negligible neutrino mass. From a combined analysis of all data, assuming three degenerate neutrino species, we measure a contribution of neutrinos to the energy density of the Universe, ω vh 2 = 0.0059 -0.0027 +0.0033 (68 per cent confidence limits), with zero falling on the 99 per cent confidence limit. This corresponds to ∼4 per cent of the total mass density of the Universe and implies a species-summed neutrino mass ∑ i m i = 0.56 -0.26 +0.30 eV, or m v ∼ 0.2 eV per neutrino. We examine possible sources of systematic uncertainty in the results. Combining the CMB, large-scale structure and cluster baryon fraction data, we measure an amplitude of mass fluctuations on 8 h -1 Mpc scales of σ 8 = 0.74 -0.07 +0.12, which is consistent with measurements based on the X-ray luminosity function and other studies of the number density and evolution of galaxy clusters. This value is lower than that obtained when fixing a negligible neutrino mass (σ 8 = 0.86 -0.07 +0.08). The combination of CMB, large-scale structure and cluster baryon fraction data also leads to remarkably tight constraints on the Hubble constant, H 0 = 68.4 -1.4 +2.0 km s -1 Mpc -1, mean matter density, ω m = 0.31 ± 0.02, and physical baryon density, ω b h 2 = 0.024 ± 0.001, of the Universe.
    Original languageEnglish
    Pages (from-to)593-600
    Number of pages7
    JournalMonthly Notices of the Royal Astronomical Society
    Volume346
    Issue number2
    DOIs
    Publication statusPublished - 1 Dec 2003

    Keywords

    • Cosmic microwave background
    • Cosmological parameters
    • Dark matter
    • Large-scale structure of Universe
    • X-rays: galaxies: clusters

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