Gravitational Waves (and Non-Gaussianity) from Cosmic Defects. A Universal Result.

I showed how a scale-invariant background of gravitational waves is always generated during 
the evolution of a network of cosmic defects in scaling regime. This is a universal result, 
independent of the nature of the defects (domain walls, strings, monopoles, textures, etc), 
and independent of the type of phase transition (1st order, 2nd order, cross-over) at which 
the defects are created. It is just a consequence of scaling, which ultimately is due to causality.

I also discussed about Non-Gaussianity from cosmic defects, albeit more briefly.