Dark Matter Distribution Induced by a Cosmic String Wake in the Nonlinear Regime

TL;DR

This paper investigates how cosmic string wakes influence dark matter distribution in the nonlinear regime using N-body simulations, identifying wake signatures at high redshifts for tensions near current observational limits.

Contribution

It introduces wavelet and ridgelet-like statistics tailored to detect cosmic string wake signals within complex dark matter distributions in nonlinear regimes.

Findings

String wakes produce detectable planar overdensities at early times.

Wake signatures can be identified down to redshift z=10 for Gμ=10^{-7}.

Disruption of wakes by Gaussian fluctuations occurs over time.

Abstract

We study the distribution of dark matter in the nonlinear regime in a model in which the primordial fluctuations include, in addition to the dominant primordial Gaussian fluctuations generated by the standard $\Lambda CDM$ cosmological model, the effects of a cosmic string wake set up at the time of equal matter and radiation, making use of cosmological $N$-body simulations. At early times the string wake leads to a planar overdensity of dark matter. We study how this non-Gaussian pattern of a cosmic string wake evolves in the presence of the Gaussian perturbations, making use of wavelet and ridgelet-like statistics specifically designed to extract string wake signals. At late times the Gaussian fluctuations disrupt the string wake. We find that for a string tension of $G \mu = 10^{-7}$, a value just below the current observational limit, the effects of a string wake can be identified in the dark matter distribution, using the current level of the statistical analysis, down to a redshift of $z = 10$.