Group infall of substructures on to a Milky Way-like dark halo

We report the discovery that substructures/subhaloes of a galaxy-size halo tend to fall ill together in groups ill cosmological simulations, something that, may explain the oddity of the MW satellite distribution. The original clustering at the time of infall is still discernible ill the angular momenta of the subhaloes even for events which took place ill) to eight, Gyrs ago, z similar to 1. This phenomenon appears to be rather common since at least 1/3 of the present-day subhaloes have fallen ill groups in our simulations. Hence, this may well explain the Lynden-Beil & Lynden-Bell ghostly streams. We have also found that; the probability of building up a flattened distribution similar to the MW satellites is as high as similar to 80% if the MW satellites were from only one group mid similar to 20% when five groups are involved. Therefore, we conclude, that the 'peculiar' distribution of satellites around the MW call be expected with the CDM structure Formation theory. This non-random assignment, of satellites to subhaloes implies an environmental dependence oil whether these low-mass objects are able to form stars, possibly related to the nature of reionization in the early Universe.