The intrinsic B-mode polarisation of the Cosmic Microwave Background
- Institute of Cosmology and Gravitation, University of Portsmouth, Burnaby Road, Portsmouth PO1 3FX (United Kingdom)
- Physik Department T31, Technische Universität München, James-Franck-Straße 1, D–85748 Garching (Germany)
We estimate the B-polarisation induced in the Cosmic Microwave Background by the non-linear evolution of density perturbations. Using the second-order Boltzmann code SONG, our analysis incorporates, for the first time, all physical effects at recombination. We also include novel contributions from the redshift part of the Boltzmann equation and from the bolometric definition of the temperature in the presence of polarisation. The remaining line-of-sight terms (lensing and time-delay) have previously been studied and must be calculated non-perturbatively. The intrinsic B-mode polarisation is present independent of the initial conditions and might contaminate the signal from primordial gravitational waves. We find this contamination to be comparable to a primordial tensor-to-scalar ratio of r ≅ 10{sup −7} at the angular scale ℓ ≅ 100, where the primordial signal peaks, and r ≅ 5 × 10{sup −5} at ℓ ≅ 700, where the intrinsic signal peaks. Therefore, we conclude that the intrinsic B-polarisation from second-order effects is not likely to contaminate future searches of primordial gravitational waves.
- OSTI ID:
- 22373476
- Journal Information:
- Journal of Cosmology and Astroparticle Physics, Vol. 2014, Issue 07; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 1475-7516
- Country of Publication:
- United States
- Language:
- English
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