SECONDARY INFALL MODEL OF GALACTIC HALO FORMATION AND THE SPECTRUM OFCOLD DARK-MATTER PARTICLES ON EARTH

The spectrum of cold dark matter particles on Earth is expected to hav e peaks in velocity space associated with particles which are falling onto the Galaxy for the first time and with particles which have falle n in and out of the Galaxy only a small number of times in the past. W e obtain estimates for the velocity magnitudes and the local densities of the particles in these peaks. To this end we use the secondary inf all model of galactic halo formation which we have generalized to take account of the angular momentum of the dark matter particles. The new model is still spherically symmetric and it admits self-similar solut ions. In the absence of angular momentum, the model produces flat rota tion curves for a large range of values of a parameter epsilon which i s related to the spectrum of primordial density perturbations. We find that the presence of angular momentum produces an effective core radi us; i.e., it makes the contribution of the halo to the rotation curve go to zero at zero radius. The model provides a detailed description o f the large scale properties of galactic halos including their density profiles, their extent, and total mass. We obtain predictions for the kinetic energies of the particles in the velocity peaks and estimates for their local densities as functions of the amount of angular momen tum, the age of the Universe, and epsilon.