Contribution of domain wall networks to the CMB power spectrum

TL;DR

This paper models domain wall networks across cosmic eras to compute their impact on the CMB power spectrum, providing the first quantitative constraint on their surface tension using simulations and MCMC analysis.

Contribution

It introduces a comprehensive simulation-based approach to quantify domain wall effects on the CMB and derives the first constraint on their surface tension from observational data.

Findings

Domain wall energy scale constrained to 0.93 MeV

First quantitative limit on domain wall surface tension

Simulations cover radiation to dark energy eras

Abstract

We use three domain wall simulations from the radiation era to the late time dark energy domination era based on the PRS algorithm to calculate the energy-momentum tensor components of domain wall networks in an expanding universe. Unequal time correlators in the radiation, matter and cosmological constant epochs are calculated using the scaling regime of each of the simulations. The CMB power spectrum of a network of domain walls is determined. The first ever quantitative constraint for the domain wall surface tension is obtained using a Markov chain Monte Carlo method; an energy scale of domain walls of 0.93 MeV, which is close but below the Zel'dovich bound, is determined.