We study the distortions induced by peculiar velocities on the redshift-space correlation function of galaxies of different morphological types in the Pisces-Perseus redshift survey. Redshift-space distortions affect early- and late-type galaxies in different ways. In particular, at small separations the dominant effect comes from virialized cluster cores, where ellipticals are the dominant population. The net result is that a meaningful comparison of the clustering strength of different morphological types can be performed only in real space, i.e., after projecting out the redshift distortions on the two-point correlation function ξ(rp, π). A power-law fit to the projected function wp(rp) on scales smaller than 10 h-1 Mpc gives r0=8.35+0.75-0.76 h-1 Mpc, γ=2.05+0.10-0.08 for the early-type population, and r0=5.55+0.40-0.45 h-1 Mpc, γ=1.73+0.07-0.08 for spirals and irregulars. These values are derived for a sample luminosity limited to MZw <= -19.5. We detect a 25% increase of r0 with luminosity for all types combined, from MZw = -19 to -20. In the framework of a simple stable clustering model for the mean streaming of pairs, we estimate σ12(1), the one-dimensional pairwise velocity dispersion between 0 and 1 h-1 Mpc, to be 865+250-165 km s-1 for early-type galaxies and 345+95-65 km s-1 for late types. This latter value should be a fair estimate of the pairwise dispersion for ``field'' galaxies; it is stable with respect to the presence or absence of clusters in the sample, and is consistent with the values found for noncluster galaxies and IRAS galaxies at similar separations.
The Astrophysical Journal
- Pub Date:
- November 1997
- Galaxies: Clusters: General;
- Galaxies: Distances and Redshifts;
- Galaxies: Structure;
- 17 LaTeX pages including 3 tables, plus 11 PS figures. Uses AASTeX macro package (aaspp4.sty) and epsf.sty. To appear on ApJ, 489, Nov 1997