Clustering of Loose Groups and Galaxies in the Perseus-Pisces Survey

We investigate the clustering properties of loose groups in the Perseus-Pisces redshift survey. Previous analyses based on CfA and SSRS surveys led to apparently contradictory results. We investigate the source of such discrepancies, finding satisfactory explanations for them. Furthermore, we find a definite signal of group clustering, whose amplitude A_G exceeds the amplitude A_g of galaxy clustering (A_G = 14.5^+3.8_-3.0, A_g=7.42^+0.20_-0.19 for the most significant case; distances are measured in h^-1 Mpc). Groups are identified with the adaptive friends-of-friends (FOF) algorithms HG (Huchra & Geller) and NW (Nolthenius & White). We debate the dependence of clustering parameters on group individuation recipes, systematically varying all search parameters. Correlation strength is especially sensitive to the sky link D_L (increasing for stricter normalization D₀) and to the (depth m_lim of the) galaxy data. It is only moderately dependent on the galaxy luminosity function φ(L), while it is almost insensitive to the redshift link V_L (both to the normalization V₀ and to the scaling recipes HG or NW).