LARGE-AMPLITUDE ISOTHERMAL FLUCTUATIONS AND HIGH-DENSITY DARK-MATTER CLUMPS

Large-amplitude isothermal fluctuations in the dark-matter energy density, parametrized by PHI = deltarho(DM)/rho(DM), are studied within the framework of a spherical collapse model. For PHI greater than or similar to 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 rho(F) almost-equal-to 140PHI3(PHI + 1)rho(eq) where rho(eq) is the matter density at equal matter and radiation energy density. This expression is valid for the entire range of possible values of PHI, both for PHI much greater than 1 and PHI much less than 1. Some astrophysical consequences of high-density dark-matter clumps are discussed.