Evidence for quasi-periodic oscillations in the recurrent emission from magnetars and their implications on the neutron star properties and equation of state

摘要: We present an analysis of highly magnetized neutron stars "magnetars", in search for high frequency oscillations the recurrent emission from soft gamma repeater SGR 1806-20, and we discuss physical interpretation these its implications on star properties structure. evidence Quasi-Periodic Oscillations (QPOs) outburst activity 1806-20 using RXTE observations. By searching timing signals at frequencies QPOs discovered 2004 December 27 giant flare source, find three 84, 103, 648 Hz different bursts. The first two lie within 8.85% 11.83%, respectively, 92 QPO detected flare. third 3.75% 625 also same are found bursts with durations, morphologies, brightness, vindicated by Monte Carlo simulations. candidate higher other lower statistical significance. fact that can relatively close to those is intriguing offer insight about origin oscillations. confront our findings against available theoretical models QPOs. leading magnetar suggests toroidal seismic oscillatory modes most likely be excited a crustquake crust. Other have been proposed explain phenomena including magnetospheric oscillations, magnetic flux tubes passive debris disk. Theoretical modeling observation will very useful putting stringent constraints equation state.