Abstract By identifying quasiperiodic oscillations (QPOs) reported in FRB 20240114A (from the Five-hundred-meter Aperture Spherical Telescope) with neutron star (NS) crustal torsional oscillations, together with experimental constraints on the incompressibility K 0 of symmetric nuclear matter at saturation density, we constrain the mass and radius of an extragalactic NS at redshift z ≈ 0.13. Identifying the low-order QPO frequencies as fundamental oscillations, and frequencies of 567.7 or 655.5 Hz (rest frame) as first overtone candidates, implies NS mass ranges of 1.00–1.55 M ⊙ or 1.17–1.76 M ⊙ , respectively. The radius is also constrained, with a self-consistent value of around 13 km, consistent with the calculation of the NS structure within the low-mass/low-central density regime. Simultaneously, we also constrain another nuclear saturation parameter, namely, the density dependence of the nuclear symmetry energy at saturation density (i.e., the slope parameter), L , and determine it to be L = 59.5–96.8 MeV with ∼10% systematic uncertainty, which is broadly consistent with previous constraints on L obtained from experiments and astronomical observations. Thus, a mapping of fast radio burst (FRB) QPOs to crustal torsional modes seems reasonable. This interpretation will be tested with the discovery of additional QPOs in upcoming FRB surveys.
Sotani et al. (Thu,) studied this question.