Compact Groups in the SDSS

EUGENIA DIAZ-GIMENEZ; CINTHIA RAGONE-FIGUEROA; HERNÁN MURIEL; ARIEL ZANDIVAREZ

Pucón, Chile

Congreso; XI Reunion Regional Latinoamericana de Astronomía; 2005

We identify compact groups in the Sloan Digital Sky Survey (SDSS) using an algorithm similar to that developed by Lee et al. (2003, astro-ph 0312553). Given that some authors claim compact groups to be chance alignments of galaxies or diffuse galaxy groups cores (Zandivarez et al. 2003, MNRAS, 340,1400), our intention is to make a statistical study of the amount 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 thefriend of-friends algorithm developed by Huchra & Geller (1982, ApJ, 257, 423).