Earth-mass dark matter microhalos with sizes of ~100 AU are the first structures to form in the Universe, if the dark matter fluid is made up of neutralinos. The existence and mass-scale of these smallest objects depends on the existence of a cutoff in the matter power spectrum (in analogy to the case of warm dark matter); the simulation depicted here shows the dark matter density field, which appears "smoother" than is typical of the CDM case with no cutoff.

Methods: CIC projections; 2D colormap (density and velocity)