Kavli Affiliate: Toshiya Namikawa
| First 5 Authors: Toshiya Namikawa, , , ,
| Summary:
We for the first time constrain anisotropic cosmic birefringence generated at
reionization using Planck PR4 polarization data. Several recent analyses of
WMAP and Planck polarization data have found a tantalizing hint of isotropic
cosmic birefringence. Ongoing and future CMB experiments will test isotropic
cosmic birefringence by improving the absolute angle calibration and
understanding the intrinsic parity-odd power spectrum of the Galactic
foregrounds. Alternatively, measuring anisotropies in cosmic birefringence and
its time evolution is also a key observable to confirm the signal of cosmic
birefringence and to investigate its origin. We discuss estimators of
anisotropic cosmic birefringence generated at different redshifts. We then
estimate anisotropic cosmic birefringence generated at reionization from the
PR4 data, showing that the power spectrum is consistent with null. We find that
the model proposed by Ferreira et al. (2024) is still consistent with the
observation. Future full-sky CMB experiments such as LiteBIRD and PICO will
help tighten the tomographic constraint to test models of cosmic birefringence.
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