CCAPP Seminar: "Exploring circular polarization in the CMB due to conventional sources of cosmic birefringence" Paulo Montero Camacho (OSU Physics)

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July 17, 2018
11:30AM - 12:30PM
Location
PRB 4138

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Add to Calendar 2018-07-17 11:30:00 2018-07-17 12:30:00 CCAPP Seminar: "Exploring circular polarization in the CMB due to conventional sources of cosmic birefringence" Paulo Montero Camacho (OSU Physics) The circular polarization of the Cosmic Microwave Background (CMB) is usually taken to be zero since it is not generated by Thomson scattering. In this talk I will discuss possible methods of generating circular polarization in the CMB due to propagation effects. I will only consider physics inside the Standard Model.  I will present two classes of mechanisms for birefringence: alignment of matter to produce an anisotropic susceptibility tensor, and anisotropy of the radiation field coupled to the non-linear response of the medium to electromagnetic fields;  this can occur either via photon-photon scattering (non-linear response of the vacuum); atomic hyperpolarizability (non-linear response of neutral atoms); or plasma delay (non-linear response of free electrons). The strongest effect comes from photon-photon scattering from recombination. Nevertheless, our results are consistent with a negligible circular polarization of the CMB in comparison with the linear polarization or the sensitivity of current and near-term experiments. PRB 4138 Center for Cosmology and AstroParticle Physics (CCAPP) ccapp@osu.edu America/New_York public
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The circular polarization of the Cosmic Microwave Background (CMB) is usually taken to be zero since it is not generated by Thomson scattering. In this talk I will discuss possible methods of generating circular polarization in the CMB due to propagation effects. I will only consider physics inside the Standard Model.  I will present two classes of mechanisms for birefringence: alignment of matter to produce an anisotropic susceptibility tensor, and anisotropy of the radiation field coupled to the non-linear response of the medium to electromagnetic fields;  this can occur either via photon-photon scattering (non-linear response of the vacuum); atomic hyperpolarizability (non-linear response of neutral atoms); or plasma delay (non-linear response of free electrons). The strongest effect comes from photon-photon scattering from recombination. Nevertheless, our results are consistent with a negligible circular polarization of the CMB in comparison with the linear polarization or the sensitivity of current and near-term experiments.

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