VEGAS: A VST Early-type Galaxy Survey. III. Mapping the Galaxy Structure, Interactions, and Intragroup Light in the NGC 5018 Group

摘要

Most of the galaxies in the universe today are in groups, which are key to understanding their evolution. In this work we present a new deep mosaic of 1.2?×?1.0 square degrees of the group of galaxies centered on NGC?5018, acquired at the ESO VLT Survey Telescope. We use u, g, r images to analyze the structure of the group members and to estimate the intragroup light. Taking advantage of deep and multiband photometry and of the large field of view of the VST telescope, we studied the structure of the galaxy members and the faint features leading into the intragroup space, and we give an estimate of the intragroup diffuse light in the NGC 5018 group of galaxies. We found that ~41% of the total g-band luminosity of the group is in the form of intragroup light (IGL). The IGL has a (g – r) color consistent with those of other galaxies in the group, indicating that the stripping leading to the formation of IGL is ongoing. From the study of this group we can infer that there are at least two different interactions involving the group members: one between NGC 5018 and NGC 5022, which generates the tails and ring-like structures detected in the light, and another between NGC 5022 and MCG-03-34-013, which has produced the H i tail. A minor merging event also happened in the formation history of NGC 5018 that perturbed the inner structure of this galaxy.