Speaker
Description
By identifying quasi-periodic oscillations reported in FRB 20240114A (from the Five-hundred-meter Aperture Spherical Telescope) with neutron star crustal torsional oscillations, together with experimental constraints on the nuclear saturation parameter, the incompressibility, we constrain the mass and radius of an extragalactic neutron star at redshift z=0.13. Identifying the low-order QPO frequencies as fundamental oscillations, and frequencies of 567.7 Hz or 655.5 Hz (rest frame) as first overtone candidates implies neutron star mass ranges of 1.00-1.55 solar mass or 1.17-1.76 solar mass, respectively. Additionally, accounting for the nuclear parameter dependence of low-mass neutron star structure yields an estimated radius of 12.5-13.5 km. Simultaneously, we also constrain the nuclear saturation parameter, namely the density dependence of the nuclear symmetry energy, L, and determine it to be L=59.5-96.8 MeV, which is broadly consistent with the previous constraints on L obtained from the experiments and astronomical observations. Thus, a mapping of FRB QPOs to crustal torsional modes seems reasonable. This can be investigated with upcoming FRB surveys over a broad range of redshifts and more elaborate data analyses.