Computing Microwave Background Polarization Power Spectra from Cosmic Birefringence

Abstract

We present a new publicly available code, $\texttt{class_rot}$, which modifies $\text{class}$ to enable fast non-perturbative calculation of cosmic microwave background polarization power spectra due to both isotropic and anisotropic polarization rotation from cosmic birefringence. Cosmic birefringence can arise from new parity-violating physics such as axion dark matter with a Chern-Simons coupling to photons or Faraday rotation due to a primordial magnetic field. Constraints on these effects can be obtained by comparing measurements to precise numerical calculations of the polarization power spectra. We describe the implementation of $\texttt{class_rot}$ in terms of both mathematical formalism and coding architecture. We also provide usage examples and demonstrate the accuracy of the code by comparing with simulations.

6 pages, 2 figures, submitted to PRD

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Cited by in corpus (6)

• Is cosmic birefringence due to dark energy or dark matter? A tomographic approach
• Redshift evolution of cosmic birefringence in CMB anisotropies
• LiteBIRD Science Goals and Forecasts: Primordial Magnetic Fields
• Impact of Anisotropic Birefringence on Measuring Cosmic Microwave Background Lensing
• Exact CMB B-mode power spectrum from anisotropic cosmic birefringence
• BICEP/Keck XXI: Constraints on Early-Universe Parity Violation from Multipole-Dependent Birefringence