Crab Pulsar Giant Pulses: Radio and Gamma-Ray Results
Session 93 -- Pulsars
Oral presentation, Friday, January 14, 10:15-11:45, Crystal Forum Room (Crystal City Marriott)

## [93.03] Crab Pulsar Giant Pulses: Radio and Gamma-Ray Results

S.C. Lundgren, J.M. Cordes (Cornell University), M. Ulmer, S.M. Matz, S. Lomatch (Northwestern University)

We analyze joint radio and $\gamma$-ray observations of giant radio pulses from the Crab pulsar. These bursts can be as much as 2000 times the average flux density amplitude in the radio. Fitting the giant pulse radio flux density histogram requires a two component model---a sharply peaked distribution of low intensity pulses and a power law component for giant pulses with an index of $-$3.3 and a low flux density cutoff that is 33 times the mean of the low intensity pulses. The absence of pulses at flux densities between the low intensity pulses and the smallest giant pulses suggests we are seeing two entirely different emission mechanisms. However, lack of time delay between giant pulses and average pulses ($\Delta t = 6 \pm 12 \mu s$) suggests both mechanisms operate in or near the same spatial location. We have found an upper limit on $\gamma$-ray flux variation concurrent with the giant radio bursts. Flux during giant bursts is less than twice the average level. We discuss implications of the lack of $\gamma$-ray variation on models for pulsar emission. In particular, particle flow variability scales by the same factor as $\gamma$-ray flux. In addition the limit on $\gamma$-ray variability correlated with radio flux requires $n(E) \propto E^{-1}$ for particles available to inverse compton scatter radio photons up to $\gamma$-rays. Given current understanding of pulsar emission mechanisms, we will consider the possibility of high energy emission from radio pulsars recently discovered in $\gamma$-ray source error boxes.