Measuring Cold Dark Matter Power Spectrum from Variations of Hubble Flows
نویسنده
چکیده
With Cold Dark Matter (CDM) power spectrum normalized by COBE results, its amplitude at smaller scales can be parametrized by Γ ∼ Ω0h. The expected variations of Hubble flows in two samples, the sample of 36 clusters in the Mark III catalogue, and the sample of 20 Type Ia supernovae (SNe), are calculated for the CDM power spectrum with varying Γ. The comparison between the expectations and the real variations in the data offers a bias-free way to constrain the power spectrum. The cluster sample yields Γ ≤ 0.30− 0.88(nps − 1) + 1.9(nps − 1) 2 at 95% C.L., with best fits Γ = 0.15−0.39(nps−1)+0.37(nps−1) , where nps is the spectral index of the power spectrum. The Type Ia SN sample yields Γ ≤ 0.25−0.80(nps−1)+1.6(nps−1) 2 at 95% C.L., strongly favoring lower Γ’s. The results are inconsistent with a critical-density universe with nps ∼ 0.8 and H0 ∼ 50 km/sec/Mpc.
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