Peak-peak correlations in the cosmic background radiation from cosmic strings

TL;DR

This study investigates how cosmic strings influence the cosmic microwave background's temperature fluctuations, demonstrating that two-point correlation functions can effectively detect their presence and set constraints on their tension.

Contribution

The paper introduces a method using two-point correlation functions of temperature maxima to detect cosmic strings in CMB maps, improving sensitivity over previous one-point statistics.

Findings

Detects cosmic strings with tension Gμ ≥ 1.2×10⁻⁸ in ideal conditions

Foregrounds and systematics raise the detection threshold to Gμ ≥ 9.0×10⁻⁸

Beam smearing further degrades the detection sensitivity

Abstract

We examine the two-point correlation function of local maxima in temperature fluctuations at the last scattering surface when this stochastic field is modified by the additional fluctuations produced by straight cosmic strings via the Kaiser-Stebbins effect. We demonstrate that one can detect the imprint of cosmic strings with tension $G\mu \gtrsim 1.2 \times 10^{-8}$ on noiseless $1^\prime$ resolution cosmic microwave background (CMB) maps at 95% confidence interval. Including the effects of foregrounds and anticipated systematic errors increases the lower bound to $G\mu \gtrsim 9.0\times 10^{-8}$ at $2\sigma$ confidence level. Smearing by beams of order 4' degrades the bound further to $G\mu \gtrsim 1.6 \times 10^{-7}$. Our results indicate that two-point statistics are more powerful than 1-point statistics (e.g. number counts) for identifying the non-Gaussianity in the CMB due to straight cosmic strings.