Can topological defects mimic the BICEP2 B-mode signal?
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.
Department of Theoretical Physics, University of the Basque Country UPV/EHU, 48080 Bilbao, Spain.
Joanes
J
Lizarraga
Department of Theoretical Physics, University of the Basque Country UPV/EHU, 48080 Bilbao, Spain.
Jon
J
Urrestilla
Département de Physique Théorique and Center for Astroparticle Physics, Université de Genève, Quai Ernest-Ansermet 24, CH-1211 Genève 4, Switzerland.
David
D
Daverio
Department of Physics and Astronomy, University of Sussex, Brighton BN1 9QH, United Kingdom and Department of Physics and Helsinki Institute of Physics, University of Helsinki, PL 64, FI-00014 Helsinki, Finland.
Mark
M
Hindmarsh
Département de Physique Théorique and Center for Astroparticle Physics, Université de Genève, Quai Ernest-Ansermet 24, CH-1211 Genève 4, Switzerland and African Institute for Mathematical Sciences, 6 Melrose Road, Muizenberg 7945, South Africa.
Martin
M
Kunz
Institute for Astronomy, University of Edinburgh, Royal Observatory, Edinburgh EH9 3HJ, United Kingdom.
Andrew R
AR
Liddle