First results on terrestrial gamma ray flashes from the Fermi Gamma‐ray Burst Monitor

Abstract

[1] The Gamma-ray Burst Monitor (GBM) on the Fermi Gamma-ray Space Telescope detected 12 intense terrestrial gamma ray flashes (TGFs) during its first year of observation. Typical maximum energies for most of the TGFs are ∼30 MeV, with one TGF having a 38 MeV photon; two of the TGFs are softer and longer than the others. After correcting for instrumental effects, a representative bright TGF is found to have a fluence of ∼0.7 photons cm −2 . Pulses are either symmetrical or have faster risetimes than fall times; they are well fit with Gaussian or lognormal functions. The fastest risetime observed was 7 ms, constraining the source radius to be less than about 2 km from the velocity of light. TGFs with multiple pulses separated in time have been known since their discovery; the GBM sample also includes clear cases of partially overlapping pulses. Four TGFs are associated with lightning locations from the World Wide Lightning Location Network. With the several ms absolute time accuracy of GBM, the time order can be confidently identified: one TGF occurred before the lightning, two were simultaneous, and one TGF occurred after the lightning.

High‐Energy Emissions Induced by Air Density Fluctuations of Discharges

“…They were first observed in 1994 from the Compton Gamma‐ray Observatory satellite (Fishman et al, 1994) and later confirmed by other space‐based observations (Briggs et al, 2010; Marisaldi et al, 2010; Smith et al, 2005). X‐rays have also been observed at closer proximity to the source with sensors on the ground and on balloons (Dwyer, 2004; Mallick et al, 2012; Moore et al, 2001) and in high‐voltage laboratory discharge experiments of long sparks (Babich et al, 2015; Dwyer et al, 2005; Kochkin et al, 2014, 2016).…”

Effect of near-earth thunderstorms electric field on the intensity of ground cosmic ray positrons/electrons in Tibet

“…For years, thousands of TGFs have been detected by satellitebased experiments, such as AGILE [23] and GBM-Fermi [24]. The lightning initiation and correlations with thunderstorms have also been studied in details [16,[25][26][27][28][29].…”

Lightning-generated whistler waves observed by probes on the Communication/Navigation Outage Forecast System satellite at low latitudes

“…[5] In addition to these direct, in situ observations of lightning in the ionosphere, recent measurements from satellites of terrestrial gamma radiation sources [e.g., Fishman et al, 1994;Smith et al, 2005;Briggs et al, 2010] have raised new interest in strong electric field coupling from lightning by demonstrating the influence of the lightning EMP on the upper atmosphere and ionosphere.…”