  Production of runaway electron avalanches and gamma rays originating inside
Martian dust storms are studied using Monte Carlo simulations. In the absence
of in situ measurements, we use theoretical predictions of electric fields
inside dust storms. Electrons are produced through the relativistic runaway
electron avalanches process, and energetic photons are results of the
bremsstrahlung scattering of the electrons with the air. Characteristic lengths
of the runaway electron avalanche for different electric fields and the energy
spectrum of electrons are derived and compared to their terrestrial
counterparts. It is found that it is possible for Martian dust storms to
develop energetic electron avalanches and produce large fluxes of gamma ray
photons similar to terrestrial gamma ray flashes from Earth's thunderstorms.
The phenomenon could be called Martian gamma ray flash, and due to the very
thin atmosphere on Mars, it can be observed by both ground-based instruments or
satellites orbiting the planet.
