THE 2-POINT CORRELATION-FUNCTION FOR GROUPS OF GALAXIES IN THE CENTER-FOR-ASTROPHYSICS REDSHIFT SURVEY

We compute the two-point correlation function, ξGG, in redshift space for the groups of galaxies identified by Ramella, Geller, and Huchra from the extension of the Center for Astrophysics (CfA) redshift survey. The group catalog includes galaxies with mB(0) ≤ 15.5 and covers the right ascension range 8h ≤ α ≤ 17h and the declination range 26°.5 ≤ δ < 38°.5. The amplitude and slope of ξGG agree with the values for the galaxy correlation function computed for the same region. These results also hold for a larger sample which covers the same right ascension range and the declination range 26°.5 ≤ δ < 44°.5. The amplitude of ξGG is consistent with an extrapolation of the amplitude-richness relation for rich clusters (see Bahcall) and with the density scaling of the cluster correlation function suggested by Szalay and Schramm. We examine the contribution of members of groups to the galaxy correlation function. We show that on scales less than ∼3.5h-1 Mpc intragroup pairs dominate the correlation function (the Hubble constant H0 = 100h km s-1 Mpc-1). On larger scales intergroup pairs are the largest contributors. Regardless of the density contrast for group selection, the "field" remains weakly correlated.