2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/10569Galactic collisions are normally modeled in a CDM model by assuming the DM consists of a small number of very massive objects. This note shows that the behaviour of a CDM halo during collisions depends critically on the mass of the particles that make it up, and in particular, all halo particles below a certain characteristic mass are likely to be lost.10 pages, 1 figureAstrophysicstext