Can topological defects mimic the BICEP2 B-mode signal?

Research paper by Joanes J Lizarraga, Jon J Urrestilla, David D Daverio, Mark M Hindmarsh, Martin M Kunz, Andrew R AR Liddle

Indexed on: 20 May '14Published on: 20 May '14Published in: Physical review letters


We show that the B-mode polarization signal detected at low multipoles by BICEP2 cannot be entirely due to topological defects. This would be incompatible with the high-multipole B-mode polarization data and also with existing temperature anisotropy data. Adding cosmic strings to a model with tensors, we find that B modes on their own provide a comparable limit on the defects to that already coming from Planck satellite temperature data. We note that strings at this limit give a modest improvement to the best fit of the B-mode data, at a somewhat lower tensor-to-scalar ratio of r ≃ 0.15.