As these systems do not present galaxy groups, satisfying fossil groups condition, we limit our analysis to BGGs which are at least as bright as ≤ 0.5).
The plane has been subdivided into blocks within which the probability that the halo is old or young, is given.
The cosmological dark matter simulations and the implemented semi-analytic galaxy models offer tools, needed to develop an insight into this subject.
Before these robust simulations became available in cosmological scales, an observational method for identification of old galaxy groups was developed in a pioneering study by Ponman et al. This was motivated by earlier numerical simulations suggesting that in most cases, members of compact galaxy groups could merge to form a single elliptical galaxy in a few billion years (Barnes 1989).
The study aimed at verifying the argument that galaxy groups with a large magnitude gap are formed earlier than the galaxy groups with a small magnitude gap.