Fluence distribution of terrestrial gamma ray flashes observed by the Fermi Gamma-ray Burst Monitor
Abstract
The observed γray fluence distribution of terrestrial gamma ray flashes (TGFs) detected by the Fermi Gamma-ray Burst Monitor (GBM) is altered by instrumental effects. We perform corrections for dead time, pulse pileup, and detection efficiency in a model-independent manner. A sample of 106 GBM TGFs is selected to include both TGFs that triggered GBM and weaker TGFs found using an off-line search. Detector dead time and pulse pileup lower the observed fluence of each TGF and the detection efficiency causes weaker TGFs to have a lower probability of detection than brighter TGFs. Monte Carlo simulations are performed in each case to correct for these effects. The corrected fluence distribution is well fit with a power law of index α=-2.20±0.13. This is consistent with previous estimates using other techniques. Neither a high-fluence cutoff nor a low-fluence limit is found. The fluence distribution is also expressed in units of TGF h-1 km-2 versus photons cm-2 per TGF.
- Publication:
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Journal of Geophysical Research (Space Physics)
- Pub Date:
- October 2013
- DOI:
- 10.1002/jgra.50580
- Bibcode:
- 2013JGRA..118.6644T
- Keywords:
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- tgf