Phenomenology 2023 Symposium

CMB birefringence from cosmic axion strings

9 May 2023, 18:00

15m

Lawrence Hall 207

Axion III

Speaker

Mr Ray Hagimoto (Rice U.)

Description

Axion-like particles (ALPs) can form a network of cosmic strings and domain walls that survives after recombination and leads to anisotropic birefringence of the cosmic microwave background (CMB). This effect provides a unique way of probing ALPs with masses in the range $3H_0\lesssim m_a\lesssim 3H_{\mathrm{c}\mathrm{m}\mathrm{b}}$. In this talk I discuss the two-point statistics of birefringence from axion string networks and using measurements of CMB birefringence from several telescopes, I find no evidence for axion-defect-induced anisotropic birefringence of the CMB. I extract constraints on the model parameters that include the ALP mass $m_a$, ALP-photon coupling $\mathcal{A}\propto g_{a\gamma \gamma }{f}_a$, the domain wall number $N_{\mathrm{d}\mathrm{w}}$, and parameters characterizing the abundance and size of defects in the string-wall network. Considering also recent evidence for isotropic CMB birefringence, I find it difficult to accommodate this with the non-detection of anisotropic birefringence under the assumption that the signal is generated by an ALP defect network.

Presentation materials

PHENO-2023_CMB-BIREFRINGENCE-FROM-AXION-STRINGS.pdf

PHENO-2023_CMB-BIREFRINGENCE-FROM-AXION-STRINGS.pdf

PHENO-2023_CMB-BIREFRINGENCE-FROM-AXION-STRINGS.pptx