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 ^ { +0.17 } _ { -0.07 } and \sigma _ { 8 } = 1.13 ^ { +0.22 } _ { -0.23 } .
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 .