The Pairwise Velocity Distribution of Galaxies in the Las Campanas Redshift Survey

Abstract

We present a novel measurement of the pairwise peculiar velocity distribution function of galaxies on scales $r<3200$ \kmsec in the Las Campanas Redshift Survey. The distribution is well described by a scale-independent exponential with a width $τ$ where $\sig =\sqrt{2}τ=363$ \kmsec. The signal is very stable. Results from the Northern and Southern sets of slices agree within $\pm13$ \kmsec and the fluctuations among the six individual survey slices vary as $\pm44$ \kmsec. The distribution was determined using a Fourier-space deconvolution of the redshift-space distortions in the correlation function. This technique is insensitive to the effect of rich clusters in the survey and recovers the entire distribution function rather than just its second moment. Taken together with the large effective volume of the survey $6.0\times10^6 \Mpc^3$, we believe this to be a definitive result for $r$-band selected galaxies with absolute magnitudes $-18.5 <M_r<-22.5$ and $z<0.2$.