Possible constraints on the density dependence of the nuclear symmetry energy from quasi-periodic oscillations in soft gamma repeaters

摘要: We systematically examine the fundamental frequencies of shear torsional oscillations in neutron star crusts a manner that is dependent on parameter $L$ characterizing poorly known density dependence symmetry energy. The identification lowest quasiperiodic oscillation (QPO) among observed QPOs from giant flares soft-gamma repeaters as $/ell=2$ enables us to constrain $L/ge 47.4$ MeV, which most conservative restriction obtained present work assumes mass and radius flaring stars range 1.4-1.8 $M_{/odot}$ 10-14 km. Next, we identify one by set low-lying oscillations. values can reproduce all terms coupled with part dripped neutrons via entrainment effects are then constrained 101.1 MeV $/le L /le$ 131.0 MeV. Alternatively, if only second frequency SGR 1806$-$20 has different origin, obtains relatively low ranging 58.0 85.3 seem more consistent other empirical constraints despite large uncertainties.