Abstract
Most of the matter in the universe is invisible. Such dark matters play an important role in the formation of large-scale structure. The composition of the dark matter is not unitary. In a universe with varied components of matter, a feature of clustering is as follows: if the densities ρ_1 and ρ_2, the Jeans lengths λ_(1J) and λ_(2J) of a two-component universe satisfy the relations of ρ_1ρ_2, λ_(1J)λ_(2J), the developed inhomogeneities on scales less than λ_(2J) in the nondominant component 1 are always larger than that in the dominant component 2, regardless of whether the initial perturbation is to be in 1 or in 2. This implies that it is necessary to have, at least, two non-baryonic dark matter components, dominant one is weak interacting particles with smaller mass and non-dominant one is more weak interacting particles with larger mass. All the following properties of the large-scale structure can be explained in a universe with two components ef dark matter: (ⅰ) the inhomogeneity of superclusters and voids with length scale of about 100Mpc; (ⅱ) the existence of visible objects with redshift z2; (ⅲ) the distribution of the dark matter is more uniform than that of visible objects; (ⅳ) the existence of two kinds of inos with different mass as derived by data on dwarf spheroidal galaxies.
Published Version
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