Intragroup dark matter distribution in small groups of halos in a LCDM cosmology

Abstract

We study the distribution of intragroup dark matter in small groups of dark matter halos of galaxy-like size in a LCDM cosmology. These groups are identified using a physical criterion and may be an appropriate representation of small galaxy groups. We quantify the amount of intragroup dark matter and characterize its distribution. We find that compact associations of halos, as well as those intermediate and loose groups, have rather flat intragroup dark matter profiles with logarithmic slopes of gamma ~0 and ~-0.2$, respectively. Hence, the intragroup dark matter of these halo systems does not follow the same cuspy tendency that halos of galaxies have. In intermediate and loose galaxy-size halo associations the intragroup matter tends to be <50% that of the total mass of the group, and in compact associations is <20% within their group radius.