## Abstract

B-mode polarization of the cosmic background radiation is induced from purely scalar primordial sources at second order in perturbations of the homogeneous, isotropic universe. We calculate the B-mode angular power spectrum C_{l}^{BB} sourced by the second-order scattering term in the full second-order Boltzmann equations for the polarized radiation phase-space density, which have recently become available. We find that at l ≈ 200 the second-order effect is comparable to the first-order effect for a tensor-to-scalar ratio of r = 10^{-6}, and to about 2·10 ^{-4} at l ≈ 1000. It is always negligible relative to the weak-lensing induced contribution.

Original language | English |
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Article number | 008 |

Journal | Journal of Cosmology and Astroparticle Physics |

Volume | 2011 |

Issue number | 4 |

DOIs | |

State | Published - Apr 2011 |

Externally published | Yes |

## Keywords

- CMBR polarisation
- CMBR theory