Cosmological parameters from combining the Lyman-α forest with CMB, galaxy clustering and SN constraints

We combine the Ly-alpha forest power spectrum (LYA) from the Sloan Digital Sky Survey (SDSS) and high resolution spectra with cosmic microwave background (CMB) including three-year WMAP, and supernovae (SN) and galaxy clustering constraints to derive new constraints on cosmological parameters. The existing LYA power spectrum analysis is supplemented by constraints on the mean flux decrement derived using a principle component analysis for quasar continua, which improves the LYA constraints on the linear power. We find some tension between the WMAP3 and LYA power spectrum amplitudes, at the similar to 2s level, which is partially alleviated by the inclusion of other observations: we find sigma(8) = 0.85 +/- 0.02 compared to sigma(8) = 0.80 +/- 0.03 without LYA. For the slope, we find n(s) = 0.965 +/- 0.012. We. nd no evidence for the running of the spectral index in the combined analysis, dn/d ln k = -(1.5 +/- 1.2) x 10(-2), in agreement with inflation. The limits on the sum of neutrino masses are significantly improved: Sigma m(v) < 0.17 eV at 95% (< 0.32 eV at 99.9%). This result, when combined with atmospheric and solar neutrino mixing constraints, requires that the neutrino masses cannot be degenerate, m(3)/m(1) > 1.3 (95% c. l.). Assuming a thermalized fourth neutrino, we. nd m(s) 0.26 eV at 95% c. l. and such a neutrino cannot be an explanation for the LSND results. In