Domain walls as dark energy

This is the authors' abstract. We don't add key points for this paper.

The possibility that the energy density of the Universe is dominated by a network of low-tension domain walls provides an alternative to the commonly discussed cosmological constant and scalar-field quintessence models of dark energy. We quantify the lower bound on the number density of the domain walls that follows from the observed near isotropy of the cosmic microwave background radiation. This bound can be satisfied by a strongly frustrated domain wall network. No fine tuning of the parameters of the underlying field theory model is required. We briefly outline the observational consequences of this model.