Cosmological parameters from large scale structure observations

The possibility of determining cosmological parameters on the basis of a wi de set of observational data including the Abell-ACO cluster power spectrum and mass function, peculiar velocities of galaxies, the distribution of Ly -alpha clouds and CMB temperature fluctuations is analyzed. Using a chi(2) minimization method, assuming Omega(Lambda) + Omega(matter) = 1 and no cont ribution from gravity waves, we show that this data set determines quite pr ecisely the values of the spectral index n of the primordial power spectrum , baryon, cold dark matter and massive neutrino density Omega(b), Omega(cdm ) and Omega(v) respectively, the Hubble constant h = H-0/(100km/s/Mpc) and the value of the cosmological constant, Omega(Lambda). Varying all parameters, we found that a tilted Lambda MDM model with one so rt of massive neutrinos and the parameters n = 1.12 +/- 0.10, Omega(m) = 0. 41 +/- 0.11 (Omega(Lambda) = 0.59 +/- 0.11), Omega(cdm) = 0.31 +/- 0.15, Om ega(v), = 0.059 +/- 0.028, Omega(b) = 0.039 +/- 0.014 and h = 0.70 +/- 0.12 matches observational data best. Omega(v) is higher for more species of massive neutrinos, similar to 0.1 fo r two and similar to 0.13 for three species. Omega(m) raises by similar to 0.08 and similar to 0.15 respectively. The 1 sigma (68.3%) confidence limits on each cosmological parameter, which are obtained by marginalizing over the other parameters, are 0.82 less tha n or equal to n less than or equal to 1.39, 0.19 less than or equal to Omeg a(m) less than or equal to 1 (0 less than or equal to Omega(Lambda) less th an or equal to 0.81), 0 Omega(nu) less than or equal to 0.17, 0.021 less th an or equal to Omega(b) less than or equal to 0.13 and 0.38 less than or eq ual to h less than or equal to 0.85 1.5 less than or equal to b(cl) less th an or equal to 3.5. Here b(cl) is the cluster bias parameter. The best-fit parameters for 31 models which are inside of 1 sigma range of the best mode l are presented (Table 4). Varying only a subset of parameters and fixing the others changes the resul ts. In particular, if a pure matter model (Omega(m) = 1) is assumed, MDM wi th Omega(v) = 0.22 +/- 0.08, three species of massive neutrinos and low h = 0.47 +/- 0.05 matches the observational data best. If a low density Univer se Omega(m) = 0.3 is assumed, a Lambda CDM model without hot dark matter an d high h = 0.71 matches the observational data best. If the primordial powe r spectrum is scale invariant (n = 1) a low density Universe (Omega(m) = 0. 45 +/- 0.12, h = 0.71 +/- 0.13) with very little hot dark matter (Omega(v) = 0.04 +/- 0.03, N-v = 1) becomes the best fit. It is shown also that the observational data set used here rules out the cl ass of CDM models with h greater than or equal to 0.5, scale invariant prim ordial power spectrum, zero cosmological constant and spatial curvature at very high confidence level, > 99.99%. The corresponding class of MDM models are ruled out at similar to 95% C.L.