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Dynamics of pairwise motions

Roman Juszkiewicz, Volker Springel, Ruth Durrer

astro-pharXiv:astro-ph/9812387

Abstract

We derive a simple closed-form expression, relating (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 (r) with N-body simulations, and find excellent agreement in the entire dynamical range probed by the simulations (0.1 ξ 1000). Our results can be used to estimate the cosmological density parameter, , directly from redshift-distance surveys, like Mark III.

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