Compton scattering effects on the duration of terrestrial gamma-ray flashes

Terrestrial gamma-ray flashes (TGFs) are gamma-ray bursts detected from space that are associated with lightning activity. In the present paper, we show that the shorter TGF durations (∼50 s) recently discovered by the gamma-ray burst monitor (GBM) aboard the Fermi Gamma-Ray Space Telescope are consistent with the temporal dispersion associated with the Compton scattering of photons produced by an instantaneous TGF source. This new result suggests that short TGF pulses observed from satellites correspond to very short TGF sources with durations less than ∼10 μs and that the observed long TGF pulses (≥100 μs) may be due to overlapping of emissions produced by a sequence of elementary processes with much shorter temporal durations.