Exact CMB B-mode power spectrum from anisotropic cosmic birefringence

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1. Verfasser: Namikawa, Toshiya
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Veröffentlicht: 2024
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author Namikawa, Toshiya
author_facet Namikawa, Toshiya
contents 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 $A_{\rm CB}\times10^4=1.03^{+0.91}_{-0.97}\,(2\,σ)$. The numerical code is publicly available at https://github.com/toshiyan/biref-aniso-bb/tree/main.
format Preprint
id arxiv_https___arxiv_org_abs_2404_13771
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Exact CMB B-mode power spectrum from anisotropic cosmic birefringence
Namikawa, Toshiya
Cosmology and Nongalactic Astrophysics
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 $A_{\rm CB}\times10^4=1.03^{+0.91}_{-0.97}\,(2\,σ)$. The numerical code is publicly available at https://github.com/toshiyan/biref-aniso-bb/tree/main.
title Exact CMB B-mode power spectrum from anisotropic cosmic birefringence
topic Cosmology and Nongalactic Astrophysics
url https://arxiv.org/abs/2404.13771