Giant Micropulse Emission in the Vela Pulsar at the C Band

We present here the analysis of giant micropulses from the Vela pulsar. A total of 4187 giant micropulses with peak flux density >2.5 Jy were detected during almost 4 hr of observations carried out with the Yunnan 40 m radio telescope at 6800 MHz. Nine of the giant micropulses arrived approximately 3-4 ms earlier than the peak of average pulse profile, longer than that at lower frequencies. The remaining giant micropulses were clustered into three distributions that correspond to three main emission regions, including four giant micropulses occurring on the trailing edge of the averaged profile. We find that the peak flux density distribution follows a power law with index alpha -4. Furthermore, a certain amount of memory is present from the giant micropulse waiting time distribution. Possible emission mechanisms are discussed.