CMB Distortions from Damping of Acoustic Waves Produced by Cosmic Strings

TL;DR

This paper investigates how cosmic strings damp acoustic waves in the early universe's photon-baryon fluid and calculates their impact on the cosmic microwave background's spectral distortions, finding it to be subdominant.

Contribution

It provides the first detailed calculation of CMB spectral distortions caused by cosmic string-induced acoustic wave damping.

Findings

Cosmic strings contribute minimally to CMB spectral distortions within current bounds.

Damping effects from cosmic strings are subdominant compared to primordial density perturbations.

The study quantifies the spectral distortion signatures of cosmic strings in the CMB.

Abstract

We study diffusion damping of acoustic waves in the photon-baryon fluid due to cosmic strings, and calculate the induced $\mu$- and $y$-type spectral distortions of the cosmic microwave background. For cosmic strings with tension within current bounds, their contribution to the spectral distortions is subdominant compared to the distortions from primordial density perturbations.