Cosmic Microwave Background anisotropies generated by domain wall networks

Understand

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 $1\,\,{\rm MeV}$).