Giant pulses and giant micropulses from pulsars are distinguished from normal pulsed emission by their large fluxes , rarity , approximately power-law distribution of fluxes and , typically , occurrence in restricted phase windows .
Here existing observations of flux distributions are manipulated into a common format and interpreted in terms of theories for wave growth in inhomogeneous media , with the aim of constraining the emission mechanism and source physics for giant pulses and micropulses .
Giant micropulses near 2 GHz ( PSRs B8033-45 and B1706-44 ) and 0.4 GHz ( PSR B0950+08 ) have indices \alpha = 6.5 \pm 0.7 for the probability distribution P ( E ) of the electric field E , with P ( E ) \propto E ^ { - \alpha } .
Giant pulses ( PSRs B0531+24 , B1937+214 , and B1821-24 ) have \alpha ranging from 4.6 \pm 0.2 to 9 \pm 2 , possibly increasing with frequency .
These are similar enough to regard giant micropulses and pulses as a single phenomenon with a common physical explanation .
The power-law functional form and values of \alpha observed are consistent with predictions for nonlinear wave collapse , but inconsistent with known self-organized critical systems , nonlinear decay processes , and elementary burst theory .
While relativistic beaming may be important , its statistics are yet to be predicted theoretically and collapse is currently the favored interpretation .
Other possibilities remain , including stochastic growth theory ( consistent with normal pulse emission ) and , less plausibly , refractive lensing .
Unresolved issues remain for all four interpretations and suggestions for further work are given .
The differences between normal and giant pulse emission suggest they have distinct source regions and emission processes .