Large-amplitude isothermal fluctuations and high-density dark-matter clumps

Large-amplitude isothermal fluctuations in the dark-matter energy density, parametrized by Φ≡δρDM/ρDM, are studied within the framework of a spherical collapse model. For Φ approx-gt 1, a fluctuation collapses in the radiation-dominated epoch and produces a dense dark-matter object. The final density of the virialized object is found to be ρF∼140Φ3(Φ+1)ρeq, where ρeq is the matter density at equal matter and radiation energy density. This expression is valid for the entire range of possible values of Φ, both for Φ much-gt 1 and Φ much-lt 1. Some astrophysical consequences of high-density dark-matter clumps are discussed