Micropulses, drifting subpulses, and nonradial oscillations of neutron stars

Abstract

Rotating, magnetized neutron stars can support a rich variety ofoscillation modes. The periods of the modes are estimated and comparedwith periodicities found in the pulsars. The millisecond time scalequasi-periodic micropulsations observed in PSR 2016+28 and PSR 1133+16can be identified as nonradial 1 = 0 or 1 p-mode oscillations, ifmode-beating or internal noise broadening can account for the apparentrapid variability of amplitude and frequency. Torsional oscillationsof the neutron star crusts have periods in the range of the pulsarsubpulses; and rotational splitting of modes with 1 = 2, 3, or 4can account qualitatively for subpulse drift. Long-period AlIvenmodes, as well as Tkachenko oscillations, should be excited by pulsarglitches, and postglitch data may contain direct evidence of thesemodes. Subject headings: pulsars - stars: neutron - stars: pulsation