Compact Groups: A Statistical Analysis

DÍAZ E.; RAGONE C.; MURIEL H.; ZANDIVAREZ A.

Santiago, Chile

Workshop; ESO Workshop on "Groups of Galaxies in the Nearby Universe"; 2005

European Southern Observatory

 We identify compact groups in the Sloan Digital Sky Survey (SDSS) using an algorithm similar to that developed by Lee et al. (2003). Given that some authors claim compact groups to be chance alignements of galaxies or difuse galaxy groups cores (Zandivarez et al. 2003), our intention is to make a statistical study of the fraction of compact groups that are real entities. To do so, we construct mock catalogues of the SDSS from cosmological numerical N-body simulations and identify compact groups with the previous algorithm. Next we compare them with groups identified with a tree-dimensional algorithm similar to the friend-of-friends algorithm developed by Huchra & Geller (1982).