Kavli Affiliate: Toshiya Namikawa
| First 5 Authors: Toshiya Namikawa, , , ,
| Summary:
We calculate the cosmic microwave background (CMB) $B$-mode power spectrum
resulting from anisotropic cosmic birefringence, without relying on the thin
approximation of the last scattering surface. Specifically, we consider the
influence of anisotropic cosmic birefringence arising from massless axion-like
particles. Comparing our results to those obtained using the thin
approximation, we observe a suppression in the amplitude of the $B$-mode power
spectrum by approximately an order of magnitude at large angular scales ($ell
lesssim 10$) and by a factor of two at small angular scales ($ell gtrsim
100$) when not employing the thin approximation. We also constrain the
amplitude of the angular power spectrum of the scale-invariant anisotropic
cosmic birefringence using the SPTpol $B$-mode power spectrum. We find that the
amplitude is constrained as $A_{rm
CB}times10^4=1.03^{+0.91}_{-0.97},(2,sigma)$. The numerical code is
publicly available at https://github.com/toshiyan/biref-aniso-bb/tree/main.
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