Evolution of Galaxy Types and H i Gas in Hickson Compact Groups

Abstract

Compact groups have high galaxy densities and low velocity dispersions, and their group members have experienced numerous and frequent interactions during their lifetimes. They provide a unique environment to study the evolution of galaxies. We examined the galaxies types and H i contents in groups to make a study on the galaxy evolution in compact groups. We used the group crossing time as an age indicator for galaxy groups. Our sample is derived from the Hickson Compact Group catalog. We obtained group morphology data from the Hyper-Leda database and the IR classification based on Wide-Field Infrared Survey Explorer fluxes from Zucker et al. By cross-matching the latest released ALFALFA 100% H i source catalog with supplement by data found in literature, we obtained 40 galaxy groups with H i data available. We confirmed that the weak correlation between H i mass fraction and group crossing time found by Ai & Zhu in SDSS groups also exists in compact groups. We also found that the group spiral galaxy fraction is correlated with the group crossing time, but the actively star-forming galaxy fraction is not correlated with the group crossing time. These results seem to fit with the hypothesis that the sequential acquisition of neighbors from surrounding larger-scale structures has affected the morphology transition and star formation efficiency in compact groups.