Radio Emission of PSR J0437−4715 at 327 MHz

Abstract

More than 412,000 single pulses from the brightest millisecond radio pulsar PSR J0437-4715 were obtained at 327 MHz using the Ooty Radio Telescope. This pulsar displays neither the nulling nor the systematic drifting phenomenon found in several normal (long period) pulsars. A rigorous upper limit to the percentage of nulling in PSR J0437-4715 is 0.0016%. However, its integrated profile varies on timescales ranging from ≈ 500 periods to days; the variation is slow and unlike the mode-changing phenomenon of normal pulsars. About 3% of the intensity of PSR J0437-4715 varies quasi-periodically, particularly at early pulse phases within the integrated profile. Its fluctuation spectrum has a weak feature at the mean value of 0.253 ± 0.002 cycles per period, with an average rms width of 0.067 ± 0.005 cycles per period, but both parameters vary from phase to phase within the integrated profile, which has not been noticed so far in pulsars. Our results are important to resolve the issue whether the radio emission of millisecond pulsars is similar to that of normal pulsars.