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Cosmological parameters from large scale structure observations
B. Novosyadlyj 1,
R. Durrer 2,
S. Gottlöber 3,
V.N. Lukash 4 and
S. Apunevych 1
Received 27 December 1999 / Accepted 11 February 2000
The possibility of determining cosmological parameters on the basis of a wide set of observational data including the Abell-ACO cluster power spectrum and mass function, peculiar velocities of galaxies, the distribution of Ly- clouds and CMB temperature fluctuations is analyzed. Using a minimization method, assuming and no contribution from gravity waves, we show that this data set determines quite precisely the values of the spectral index n of the primordial power spectrum, baryon, cold dark matter and massive neutrino density , and respectively, the Hubble constant km/s/Mpc) and the value of the cosmological constant, .
Varying all parameters, we found that a tilted MDM model with one sort of massive neutrinos and the parameters , (), , , and matches observational data best.
is higher for more species of massive neutrinos, for two and for three species. raises by and respectively.
The 1 (68.3%) confidence limits on each cosmological parameter, which are obtained by marginalizing over the other parameters, are , (), , and . Here is the cluster bias parameter. The best-fit parameters for 31 models which are inside of range of the best model are presented (Table 4).
Varying only a subset of parameters and fixing the others changes the results. In particular, if a pure matter model () is assumed, MDM with , three species of massive neutrinos and low matches the observational data best. If a low density Universe is assumed, a CDM model without hot dark matter and high matches the observational data best. If the primordial power spectrum is scale invariant () a low density Universe () with very little hot dark matter (, ) becomes the best fit.
It is shown also that the observational data set used here rules out the class of CDM models with , scale invariant primordial power spectrum, zero cosmological constant and spatial curvature at very high confidence level, . The corresponding class of MDM models are ruled out at C.L.
Key words: galaxies: clusters: general cosmology: theory cosmology: dark matter cosmology: large-scale structure of Universe
Send offprint requests to: Bohdan Novosyadlyj
Online publication: April 10, 2000