Compact groups in theory and practice – IV. The connection to large-scale structure

摘要: We investigate the properties of photometrically-selected compact groups (CGs) in Sloan Digital Sky Survey. In this paper, fourth a series, we focus on understanding characteristics our observed CG sample with particular attention paid to quantifying and removing contamination from projected foreground or background galaxies. Based simple comparison pairwise redshift likelihoods, nd that approximately half parent contain one more (interloping) members; nal clean contains 4566 galaxies 1086 groups. show remaining CGs are associated rich (or clusters), i.e. they embedded sub-structure. The other have spatial distributions number-density proles consistent interpretation either independently distributed structures within eld (i.e. isolated) relatively poor structures. Comparisons late-type red-sequence fractions radial annuli around apparently isolated resemble population by 300 500 kpc group centre. contrast, galaxy surrounding appears remain distinct out beyond 1 2 Mpc, results for take as additional evidence distinction between groups, vs. embedded, is separation dierent host environments.