Pulse sharpness and asymmetry in millisecond pulsars

Abstract

The light curves of radiation from antipodal caps of rapidly rotating neutron stars are calcuated with and without gravity. The light curves depend strongly on the rotation speed and on the emission spectrum and could become quite sharp. Gravity generally flattens the light curves, but it does so less for rapidly rotating neutron stars and the newly discovered PSR 1957+20, and can never flatten them enough to explain the absence of pulsation from low-mass X-ray binaries. Rotation also causes an asymmetry in the pulses similar to that caused by interstellar medium absorption or scattering.