Radio and X-ray observations of PSR B0540-69

Abstract

PSR B0540−69 is one of a small handful of pulsars known to emit giant pulses and the only extra-galactic pulsar known to do so. We observed the pulsar for a total of 72 h over a 6 month interval and detected 141 giant pulses. We have obtained correct phasing between the radio arrival times of the giant pulses and the X-ray pulse profile. The giant pulses occur in two phase windows, located 6.7 ms before and 5.0 ms after the mid-point of the X-ray profile. We have detected the integrated profile of the pulsar at 1.4 GHz with a flux density of only 24 µJy. The statistics of the giant pulses are clearly power law and it is likely that the giant pulses contribute only a few per cent of the integrated pulse flux density, similar to other pulsars with giant pulse emission. Simultaneous X-ray and radio observations show no significant increase in the X-ray flux at the time of the radio giants. The relative enhancements in the X-ray emission must be at least 5.5 times smaller than in the radio emission. Ke yw ords: pulsars: individual: PSR B0540−69.