Observational Limits on Inverse Compton Processes in GRBs

Inverse Compton (IC) scattering is one of two viable mechanisms that can produce the prompt gamma-ray emission in Gamma-Ray Bursts. IC requires low energy seed photons and a population of relativistic electrons that upscatter them. The same electrons can upscatter the gamma-ray photons to even higher energies in the TeV range. Using the current upper limits on the prompt optical emission we show here that under general conservative assumption the IC mechanism suffers from an "energy crisis". Namely, IC will over-produce a very high energy component that would carry much more energy than the observed prompt gamma-rays. Our analysis is general and it makes no assumptions on the specific mechanism that produces the relativistic electrons population.