Galaxy And Mass Assembly (GAMA): The Most Isolated GAMA Galaxies

Abstract: While galaxies generally live in clusters and groups, particularly small groups, or other structures such as walls or filaments, some galaxies appear relatively `isolated', i.e. lacking in close neighbours. Here we use the GAMA survey, and an objective measure of isolation, to explore the most isolated galaxies. We then determine whether these have particular physical characteristics. We find that, as expected, while grouped galaxies split between blue, disk-like and star forming and red, spheroidal and quiescent, isolated galaxies are preferentially the former. However, there is a broad overlap in properties, with some isolated galaxies sharing the latter characteristics. Considering only the star-forming galaxies, when controlled by mass we find no differences between the grouped and isolated galaxies in terms of their star formation and stellar populations. Given the lack of significant interactions for the isolated sample, this implies that the evolution of present-day star-forming galaxies in all environments (at least outside rich clusters) has been, and remains, dominated by internal processes.