Galaxy Groups in the SDSS-DR3

TL;DR

This paper introduces a new catalog of over ten thousand galaxy groups from SDSS-DR3, using an improved friend-of-friend algorithm that accounts for density variations and reduces artificial merging, providing valuable data for galaxy environment studies.

Contribution

The study develops an enhanced galaxy group identification method and produces a comprehensive catalog with improved accuracy over previous datasets.

Findings

Catalog contains 10,864 galaxy groups with ≥4 members

Mean redshift of the group sample is 0.1

Median velocity dispersion is 230 km/s

Abstract

We present a new sample of galaxy groups identified in the Sloan Digital Sky Survey Data Release 3. Following previous works we use the well tested friend-of-friend algorithm developed by Huchra & Geller which take into account the number density variation due to the apparent magnitude limit of the galaxy catalog. To improve the identification we implement a procedure to avoid the artificial merging of small systems in high density regions and then apply an iterative method to recompute the group centers position. As a result we obtain a new catalog with 10864 galaxy groups with at least four members. The final group sample has a mean redshift of 0.1 and a median velocity dispersion of $230 km s^{-1}$.