Probing Cosmic Strings with Satellite CMB measurements

TL;DR

This paper presents a technique for detecting cosmic strings in high-resolution CMB data, analyzing the impact of foregrounds and noise, and establishing limits on string tension based on simulated observations.

Contribution

It introduces a method to recognize Kaiser-Stebbins signatures in CMB maps and assesses the detectability threshold considering foreground contamination and instrumental sensitivity.

Findings

Detectability threshold for cosmic strings at about $G < 1.5d7 10^{-6}$

Simulations show null signals follow a chi-squared distribution

Foreground contamination limits the sky regions suitable for analysis

Abstract

We study the problem of searching for cosmic string signal patterns in the present high resolution and high sensitivity observations of the Cosmic Microwave Background (CMB). This article discusses a technique capable of recognizing Kaiser-Stebbins effect signatures in total intensity anisotropy maps, and shows that the biggest factor that produces confusion is represented by the acoustic oscillation features of the scale comparable to the size of horizon at recombination. Simulations show that the distribution of null signals for pure Gaussian maps converges to a $\chi^2$ distribution, with detectability threshold corresponding to a string induced step signal with an amplitude of about 100 $\muK$ which corresponds to a limit of roughly $G\mu < 1.5\times 10^{-6}$. We study the statistics of spurious detections caused by extra-Galactic and Galactic foregrounds. For diffuse Galactic foregrounds, which represents the dominant source of contamination, we derive sky masks outlining the available region of the sky where the Galactic confusion is sub-dominant, specializing our analysis to the case represented by the frequency coverage and nominal sensitivity and resolution of the Planck experiment.