A preference for a nonzero neutrino mass from cosmological data
Abstract
We present results from the analysis of cosmic microwave background (CMB), largescale structure (galaxy redshift survey) and Xray galaxy cluster (baryon fraction and Xray luminosity function) data, assuming a geometrically flat cosmological model and allowing for tensor components and a nonnegligible 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_{ν}h^{2}= 0.0059^{+0.0033}_{0.0027} (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 speciessummed neutrino mass , or m_{ν}~ 0.2 eV per neutrino. We examine possible sources of systematic uncertainty in the results. Combining the CMB, largescale structure and cluster baryon fraction data, we measure an amplitude of mass fluctuations on 8 h^{1} Mpc scales of σ_{8}= 0.74^{+0.12}_{0.07}, which is consistent with measurements based on the Xray 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^{+0.08}_{0.07}). The combination of CMB, largescale structure and cluster baryon fraction data also leads to remarkably tight constraints on the Hubble constant, H_{0}= 68.4^{+2.0}_{1.4} 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.
 Publication:

Monthly Notices of the Royal Astronomical Society
 Pub Date:
 December 2003
 DOI:
 10.1046/j.13652966.2003.07022.x
 arXiv:
 arXiv:astroph/0306386
 Bibcode:
 2003MNRAS.346..593A
 Keywords:

 cosmic microwave background;
 cosmological parameters;
 dark matter;
 largescale structure of Universe;
 Xrays: galaxies: clusters;
 Astrophysics;
 High Energy Physics  Phenomenology
 EPrint:
 Final version. MNRAS, in press (9 pages, 6 figures, 1 table). Includes small modification to the neutrino mass calculation and comment on quintessence. Conclusions unchanged