Non-gaussian Features of Linear Cosmic String Models

Abstract

We investigate the non-gaussian properties of cosmic-string-seeded linear density perturbations with cold and hot dark matter backgrounds, using high-resolution numerical simulations. We compute the one-point probability density function of the resulting density field, its skewness, kurtosis, and genus curves for different smoothing scales. A semi-analytic model is then invoked to provide a physical interpretation of our results. We conclude that on scales smaller than $1.5{(Ωh^2)}^{-1}$Mpc, perturbations seeded by cosmic strings are very non-gaussian. These scales may still be in a linear or mildly non-linear regime in an open or $Λ$-universe with $Γ=Ωh \lsim 0.2$.

6 pages, 6 figures; accepted by Ap. J. Lett. With error bars included in the genus curves (figure 3). Also corrected for a minor error in the standard normalization of wavenumbers $k$, resulting from using an incorrect figure for the time $t_{eq}$ of the equal matter-radiation transition given in the Kolb and Turner textbook "The Early Universe". Main conclusions remain unchanged