The author presents a simple particle-based model of dark matter in which the macroscopic properties of galactic halos emerge directly from the microscopic behavior of a hypothetic neutral, stable particle particle X with finite velocity dispersion on cosmological timescales and effectively collisionless on galactic scales. A plausible origin for such particles is in the early Universe, through a high-energy e+e- processes. The model naturally leads to a density profile proportional to 1/r2, which explains the observed flattening of rotation curves, and its regularized form provides a good agreement with observational data using a minimal set of parameters. This result supports the following interpretation: within the framework of the present model, particle dark matter can account for the gravitational dynamics of galaxies and the matter content of the Universe, but is not suitable to explain cosmic acceleration. This suggests that dark matter and dark energy should be treated as distinct components of the cosmological model.
Livio Rosai (Wed,) studied this question.