An estimate of Ω_m without priors

Abstract

Using mean relative peculiar velocity measurements for pairs of galaxies, we estimate the cosmological density parameter $\hat{I}{\text{c◯}}_m$ and the amplitude of density fluctuations $\ddot{I}{ƒ}_8$. Our results suggest that our statistic is a robust and reproducible measure of the mean pairwise velocity and thereby the $\hat{I}{\text{c◯}}_m$ parameter. We get $\hat{I}{\text{c◯}}_m=0.30_{-0.07}^{+0.17}$ and $\ddot{I}{ƒ}_8=1.13_{-0.23}^{+0.22}$. 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