24–28 Aug 2026
Leiden University
Europe/Zurich timezone

CMB birefringence from ultralight-axion string networks

Not scheduled
20m
Gorlaeus gebouw (Leiden University)

Gorlaeus gebouw

Leiden University

Einsteinweg 55, 2333 CC Leiden
Talk Cosmic Microwave Background

Speaker

Moira venegas villa

Description

Axion-like particles (ALPs) can form a network of cosmic strings that persists after recombination and induces birefringence in the cosmic microwave background (CMB), rotating the plane of polarization of propagating photons. In this work, we analyze a high-resolution simulation of an axion string network generated using adaptive mesh refinement (AMR) techniques. By performing ray tracing through the three-dimensional field configuration, we compute the cumulative rotation angle experienced by CMB photons along their line of sight from the last scattering surface to the present epoch.  Our results show how the spatial distribution and evolution of the string network imprint characteristic spatial variations in the birefringence angle, and assess their detectability with current and next-generation CMB polarization experiments.

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