Skewness in CMB temperature fluctuations from curved cosmic (super-)strings

TL;DR

This paper investigates the non-Gaussian features, including skewness, in CMB temperature fluctuations caused by curved cosmic strings, using Monte Carlo simulations to analyze their probability distribution functions.

Contribution

It introduces a simple model for curved cosmic string networks and quantifies the skewness and non-Gaussian tails in the CMB temperature fluctuation distribution.

Findings

Skewness for standard cosmic strings is approximately -0.14.

Non-Gaussian features diminish with decreasing intercommuting probability.

Skewness becomes very small (less than a few percent) for low intercommuting probabilities.

Abstract

We compute the one-point probability distribution function of small-angle cosmic microwave background temperature fluctuations due to curved cosmic (super-)strings with a simple model of string network by performing Monte Carlo simulations. Taking into account of the correlation between the curvature and the velocity of string segments, there appear non-Gaussian features, specifically non-Gaussian tails and a skewness, in the one-point pdf. The obtained sample skewness for the conventional field-theoretic cosmic strings is $g_1\approx -0.14$, which is consistent with the result reported by Fraisse et al.. We also discuss the dependence of the pdf on the intercommuting probability. We find that the standard deviation of the Gaussian part increases and non-Gaussian features are suppressed as the intercommuting probability decreases. For sufficiently small intercommuting probability, the skewness is given by $\lesssim$ (a\ few) $\times 10^{-2}$.