Morphological and Luminosity Content of Poor Galaxy Groups

Abstract

We find that the fraction of early-type galaxies in poor groups (containing from 4 to 10 members) is a weakly increasing function of the number of the group members and is about two times higher than in a sample of isolated galaxies. We also find that the group velocity dispersion increases weakly with the fraction of early-type galaxies. Early-type galaxies in poor groups are brighter in the near-infrared with respect to isolated ones by 0.75 mags (in K) and to a lesser degree (by 0.5 mags) also in the blue. We also find early-type galaxies in groups to be redder than those in the field. These findings suggest that the formation history for early-type galaxies in overdense regions is different from that of in underdense regions, and that their formation in groups is triggered by merging processes.

5 pages, 3 figures, ApJ Lett. in press

References in corpus (4)

• A Catalog of Compact Groups of Galaxies in the SDSS Commissioning Data
• Properties of Isolated Disk Galaxies
• The relation between galaxy activity and the dynamics of compact groups of galaxies
• The Shape of Poor Groups of Galaxies

Cited by in corpus (13)

• The Galaxy Content of SDSS Clusters and Groups
• The DEEP2 galaxy redshift survey: the evolution of the blue fraction in groups and the field
• The dependence on environment of Cold Dark Matter Halo properties
• Southern GEMS Groups I: Dynamical Properties
• Eridanus - A Supergroup in the Local Universe?
• The properties of early-type galaxies in the Ursa Major cluster
• The Group Evolution Multiwavelength Study (GEMS): the Sample and Datasets
• Properties of Hickson Compact Groups and of the Loose Groups within which they are Embedded
• Galaxy Evolution in Local Group Analogs. I. A GALEX study of nearby groups
• The Relation between Morphology and Dynamics of Poor Groups of Galaxies
• On the Formation of cD Galaxies and their Parent Clusters
• The double galaxy cluster Abell 2465 - II. Star formation in the cluster
• Interacting Galaxies in Sparsely Populated Groups