Constraints on Extended Axion Structures from Lensing Effects of Fast Radio Burst

Jan Tristram Acuña¹, Kuan-Yen Chou^1*, Po-Yen Tseng¹

¹Department of Physics, National Tsing Hua University, Hsinchu, Taiwan

* Presenter:Kuan-Yen Chou, email:kychou@gapp.nthu.edu.tw

Axions are hypothetical pseudoscalar particles that were initially proposed to address the strong CP problem and now have gained attention as potential candidates for dark matter. Both QCD axions and axion-like particles have the potential to form an astrophysical compact star known as axion star through gravitational attraction and self-interaction processes in the early universe. In this work, we explore the lensing effect of fast radio bursts (FRBs) induced due to both gravity and axion-photon coupling effects, while the latter effect hasn’t been considered in the past literature. We compute the integrated optical depth of FRB being lensed by axion stars located in both extragalactic space and the Milky Way. Using the absence of observed lensed FRB signals, we have placed the constraints on axion parameters, such as mass, decay constant, axion-photon coupling constant, and its fraction to dark matter abundance.

Keywords: Dark Matter, Axion, Axion-Photon Coupling, Lensing Effect, Fast Radio Burst