Current status of models with hot and cold dark matter
| Autor: | A. M. Malinovskii, N. A. Arkhipova, E. V. Mikheeva, V. N. Lukash |
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| Rok vydání: | 2001 |
| Předmět: | |
| Zdroj: | Astronomy Reports. 45:163-172 |
| ISSN: | 1562-6881 1063-7729 |
| DOI: | 10.1134/1.1353356 |
| Popis: | An analysis of a five-parameter family of cosmological models in a spatially flat Friedmann Universe with a zero Λ term is presented. The five parameters are (1) σ8, the dispersion of the mass fluctuations in a sphere with radius 8h −1 Mpc, where h=H 0/100 km s−1 Mpc−1 and H 0 is the Hubble constant; (2) n, the slope of the density-perturbation spectrum; (3) Ωv, the normalized energy density of hot dark matter; (4) Ωb, the baryon density; and (5) h, the normalized Hubble constant. The density of cold dark matter is determined from the condition Ω cdm >1−Ωv−Ω b . Analysis of the models is based on comparison of computational results with observational data for: (1) the number density and mass function of galaxy clusters (a so-called Press-Schechter formalism) and (2) the cosmic microwave background anisotropy. The first method enabled us to determine the value σ8=0.52±0.01 with high accuracy. Using the resulting normalization of the density-perturbation spectrum, we calculated a model for the anisotropy of the cosmic microwave background radiation on large scales (l⋍10, where l is the harmonic number) and the required contribution of cosmological gravitational waves, characterized by the parameter T/S. The restrictions on T/S become weaker as Ωv increases. Nevertheless, even when Ωv≤0.4, models with h+n≥1.5 require a considerable contribution from gravitational waves: T/S≳0.3. On the other hand, in models with Ωv≤0.4 and a scale-invariant density-perturbation spectrum (n=1), we find T/S ≳10(h−0.47). The minimization of T/S is possible only for the family of models with red spectra (n |
| Databáze: | OpenAIRE |
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