An estimate of Ω_m without priors

Abstract

Using mean relative peculiar velocity measurements for pairs of galaxies, we estimate the cosmological density parameter ${\Omega }_m$ and the amplitude of density fluctuations ${\sigma }_8$. Our results suggest that our statistic is a robust and reproducible measure of the mean pairwise velocity and thereby the ${\Omega }_m$ parameter. We get ${\Omega }_m=0.30_{-0.07}^{+0.17}$ and ${\sigma }_8=1.13_{-0.23}^{+0.22}$. These estimates do not depend on prior assumptions on the adiabaticity of the initial density fluctuations, the ionization history, or the values of other cosmological parameters.

12 pages, 4 figures, slight changes to reflect published version

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