Probing nuclear bubble structure via neutron star asteroseismology

摘要: We consider torsional oscillations that are trapped in a layer of spherical-hole (bubble) nuclear structure, which is expected to occur the deepest region inner crust neutron star. Because this intervenes between phase slab nuclei and outer core uniform matter, bubble can be excited separately from usual crustal oscillations. find eigenmode analyses for various models equation state matter fundamental frequencies such almost independent incompressibility symmetric but strongly depend on slope parameter symmetry energy $L$. Although also sensitive entrainment effect, i.e., what portion nucleons outside bubbles contribute oscillations, by having fixed, we successfully fit calculated inside star specific mass radius as function By comparing resultant fitting formula quasi-periodic (QPOs) observed soft-gamma repeaters, each low-frequency QPOs identified either oscillation or oscillation, given generally accepted values $L$ all stellar considered here.