Detecting Extragalactic Axion-like Dark Matter with Polarization Measurements of Fast Radio Bursts

Axions or axion-like particles (ALPs) are one of the promising dark matter (DM) candidates. A prevalent method to detect axion-like DM is to seek periodic oscillation in the polarization angles (PAs) of linearly polarized light emitted from astrophysical sources. In this work, we use the time-resolved polarization measurements of the hyperactive repeating fast radio burst, FRB 20220912A, detected by the Five-hundred-meter Aperture Spherical radio Telescope (FAST) to search for extragalactic axion-like DM. Given a DM density profile of FRB 20220912A’s host, we obtain upper limits on the ALP-photon coupling constant of $g_{a\gamma }<(3.4\times {10}^{-11}-1.9\times {10}^{-9}){\mathrm{G}\mathrm{e}\mathrm{V}}^{-1}$ for the ALP masses $m_a\sim (1.4\times {10}^{-21}-5.2\times {10}^{-20})\mathrm{e}\mathrm{V}$. Persistent polarimetric observations with FAST would extend the constraints to lower masses. Although the $g_{a\gamma }$ constraints derived from FRBs are less competitive than those from other methods, FRBs offer an alternative way to detect axion-like DM on extragalactic distance scales, complementary to galactic DM probes.