The Global 21 cm Signal of a Network of Cosmic String Wakes

TL;DR

This paper investigates how a network of cosmic string wakes influences the global 21 cm brightness temperature, showing potential enhancements up to 100% for certain string tensions, impacting the interpretation of early universe signals.

Contribution

It extends previous single-wake models to a network of wakes during the matter era and quantifies the resulting enhancement in the 21 cm signal.

Findings

Network of wakes can double the 21 cm brightness temperature.

Enhancement depends on cosmic string tension, between 10% and 100%.

Impacts interpretation of Wouthuysen-Field absorption measurements.

Abstract

In previous works we discussed the 21 cm signature of a single cosmic string wake. However the 21 cm brightness temperature is influenced by a network of cosmic string wakes, and not one single wake. In this work we consider the signal from a network of wakes laid down during the matter era. We also improve on the previous calculation of a single wake signature. Finally we calculate the enhancement of the global 21 cm brightness temperature due to a network of wakes and discuss its affects of the signal measured in the Wouthuysen-Field absorption trough. We estimated that for string tensions between $10^{-8}$ to $10^{-7}$ there would be between a 10% to a factor 2 enhancement in the signal.