A Study of Giant Pulses from PSR J1824−2452A

We have searched for microsecond bursts of emission from millisecond pulsarsin the globular cluster M28 using the Parkes radio telescope. We detected atotal of 27 giant pulses from the known emitter PSR J1824-2452A. At wavelengthsaround 20 cm the giant pulses are scatter-broadened to widths of around 2microseconds and follow power-law statistics. The pulses occur in two narrowphase-windows which correlate in phase with X-ray emission and trail the peaksof the integrated radio pulse-components. Notably, the integrated radioemission at these phase windows has a steeper spectral index than otheremission. The giant pulses exhibit a high degree of polarization, with manybeing 100% elliptically polarized. Their position angles appear random.Although the integrated emission of PSR J1824-2452A is relatively stable forthe frequencies and bandwidths observed, the intensities of individual giantpulses vary considerably across our bands. Two pulses were detected at both2700 and 3500 MHz. The narrower of the two pulses is 20 ns wide at 3500 MHz. At2700 MHz this pulse has an inferred brightness temperature at maximum of 5 x10^37 K. Our observations suggest the giant pulses of PSR J1824-2452A aregenerated in the same part of the magnetosphere as X-ray emission through adifferent emission process to that of ordinary pulses.Comment: Accepted by Ap