Cosmic Microwave Background anisotropies generated by domain wall networks

TL;DR

This paper introduces a numerical tool to efficiently compute CMB anisotropies caused by domain wall networks, extending existing codes and models to better understand their cosmological impact.

Contribution

The authors adapt the Unconnected Segment model for cosmic strings to describe domain wall networks, enabling fast computation of their CMB signatures.

Findings

Derived a new constraint on the domain wall energy scale: η < 0.92 MeV.

Extended the CMBACT code to include domain wall networks.

Provided detailed power spectra for domain wall-induced CMB anisotropies.

Abstract

We develop a numerical tool for the fast computation of the temperature and polarization power spectra generated by domain wall networks, by extending the publicly available CMBACT code --- that calculates the CMB signatures generated by active sources --- to also describe domain wall networks. In order to achieve this, we adapt the Unconnected Segment model for cosmic strings to also describe domain wall networks, and use it to model the energy-momentum of domain wall networks throughout their cosmological history. We use this new tool to compute and study the TT, EE, TE and BB power spectra generated by standard domain wall networks, and derive a conservative constraint on the energy scale of the domain wall-forming phase transition of $\upeta <0.92\,\,{\rm MeV}$ (which is a slight improvement over the original Zel'dovich bound of $1\,\,{\rm MeV}$).