2013/03/31 by Hajime Sotani, Ken’ichiro Nakazato, Ken'ichiro Nakazato +2 · 2 citations
Earth and Planetary Sciences · Physics and Astronomy · #Astrophysics #Condensed matter physics #Gamma-ray bursts and supernovae #High-pressure geophysics and materials #Neutron #Neutron star #Nuclear physics #Oscillation (cell signaling) #Physics #Pulsars and Gravitational Waves Research #Quasiperiodic function #RADIUS #Symmetry (geometry) #astro-ph.HE #nucl-th
paper · pdf · doi:10.1093/mnras/stt1152
published as Mon.Not.Roy.Astron.Soc.434:2060,2013 · accepted for publication in MNRAS
arxiv created 2013/06/21 · openalex publication_date 2013/07/18 · arxiv updated 2013/08/27 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
We systematically examine the fundamental frequencies of shear torsional oscillations in neutron star crusts in a manner that is dependent on the parameter L characterizing the poorly known density dependence of the symmetry energy. The identification of the lowest quasi-periodic oscillation (QPO) among the observed QPOs from giant flares in soft-gamma repeaters as the ℓ = 2 fundamental torsional oscillations enables us to constrain the parameter L as L ≥ 47.4 MeV, which is the most conservative restriction on L obtained in the present work that assumes that the mass and radius of the flaring neutron stars range 1.4–1.8 M⊙ and 10–14 km. Next, we identify one by one a set of the low-lying frequencies observed in giant flares as the fundamental torsional oscillations. The values of L that can reproduce all the observed frequencies in terms of the torsional oscillations coupled with a part of dripped neutrons via entrainment effects are then constrained as 101.1 ≤ L ≤ 131.0 MeV. Alternatively, if only the second lowest frequency observed in SGR 1806−20 has a different origin, one obtains relatively low L values ranging 58.0 ≤ L ≤ 85.3 MeV, which seem more consistent with other empirical constraints despite large uncertainties.