Possible identifications of newly observed magnetar quasi-periodic oscillations as crustal shear modes

摘要: Abstract Quasi-periodic oscillations (QPOs) discovered in soft-gamma repeaters (SGRs) are expected to help us study the properties of matter neutron stars. In earlier investigations, we identified QPOs frequencies below ∼100 Hz observed giant flares SGR 1806 − 20 and 1900+14 as crustal torsional oscillations. For this purpose, calculated fundamental with various angular indices l, by changing stellar mass radius. work, try explain additional QPO recently reported Huppenkothen et al. (2014a, 2014b) within same framework before except that newly take into account effect electron screening, which acts decrease a small amount. Those were two different SGRs, i.e., J1550 5418. Then, find frequency can be still one oscillations, while those 5418 also explained terms although relevant difficult identify.