Dynamics of pairwise motions
arXiv:astro-ph/9812387 · doi:10.1086/312055
Abstract
We derive a simple closed-form expression, relating $\vs(r)$ -- the mean relative velocity of pairs of galaxies at fixed separation $r$ -- to the two-point correlation function of mass density fluctuations, $ξ(r)$. We compare our analytic model for $\vs(r)$ with N-body simulations, and find excellent agreement in the entire dynamical range probed by the simulations ($0.1 \lsim ξ\lsim 1000$). Our results can be used to estimate the cosmological density parameter, $\Om$, directly from redshift-distance surveys, like Mark III.
10 pages 2 Figs., submitted to ApJ Lett