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

Large-amplitude isothermal fluctuations in the dark-matter energy density, parametrized by {Φ}{≡}{δ}ρDM/ρDM, are studied within the framework of a spherical collapse model. For {Φ}{}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}{}1 and {Φ}{}1. Some astrophysical consequences of high-density dark-matter clumps are discussed.