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 gaγ < (3.4 × 10−11−1.9 × 10−9) GeV−1 for the ALP masses ma ~ (1.4 × 10−21−5.2 × 10−20) eV. Persistent polarimetric observations with FAST would extend the constraints to lower masses. Although the gaγ 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. Axion-like particles (ALPs), a type of ultralight bosons, have emerged as a likely candidate in the search for dark matter. The authors use polarization data from a repeating Fast Radio Burst (FRB) to constrain the photon coupling constant via polarization angle variations of linearly polarized emission and under the assumption that ALPs compose all the dark matter in the Universe.