How to Derotate the Cosmic Microwave Background Polarization
If the linear polarization of the cosmic microwave background is rotated in a frequency-independent manner as it propagates from the surface of last scatter, it may introduce a B-mode polarization. Here I show that measurement of higher-order TE, EE, EB, and TB correlations induced by this rotation can be used to reconstruct the rotation angle as a function of position on the sky. This technique can be used to distinguish primordial B modes from those induced by rotation. The effects of rotation can be distinguished geometrically from similar effects due to cosmic shear.
Additional Information© 2009 The American Physical Society. Received 7 October 2008; revised 12 February 2009; published 19 March 2009. I thank A. Cooray, C. Hirata, and V. Gluscevic for useful comments. This work was supported by DoE Grant No. DE-FG03-92-ER40701.
Published - Kamionkowski2009p1320Phys_Rev_Lett.pdf