Fluctuations of cosmological birefringence and the effect on CMB B-mode polarization [CL]

http://arxiv.org/abs/1403.3997


The cosmological birefringence caused by the coupling between the cosmic scalar field and the cosmic microwave background (CMB) photons through the Chern-Simons term can rotate the polarization planes of the photons, and mix the CMB E-mode and B-mode polarizations. The rotation angle induced by the dynamical scalar field can be separated into the isotropic background part and the anisotropic fluctuations. The effect of the background part has been be studied in the previous work (Zhao & Li, arXiv:1402.4324). In this paper, we focus on the influence of the anisotropies of the rotation angle. We find that, if the cosmic scalar field is identified as the quintessence field, the anisotropies of the rotation angle are always too small to be detectable. However, if the scalar field is massless, the rotation spectrum can be quite large, which may be detected by the potential CMB observations. In addition, we find that, the rotated B-mode polarization could be fairly large, and comparable with those generated by relic gravitational waves or cosmic weak lensing, which forms a new contamination for the detection of relic gravitational waves in the CMB. In this paper, we also propose the method to reconstruct and subtract the rotated B-mode polarization, by which the residuals become negligible for the gravitational-wave detection.

Read this paper on arXiv…

W. Zhao and M. Li
Tue, 18 Mar 14
45/62