Dynamics of pairwise motions

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, $\xi (r)$. 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

References in corpus (3)

• Clustering of Galaxies in a Hierarchical Universe: I. Methods and Results at z=0
• The Most Massive Distant Clusters: Determining Omega and sigma_8
• Streaming velocities as a dynamical estimator of Omega

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