Particle accelerators in the sky: The physics of terrestrial gamma-ray flashes

by Dr Christoph Köhn (Technische Universität Dänemark)

Thursday 19 Oct 2023, 16:00 → 17:00 Europe/Berlin

CP-03-123 (TU Dortmund)

Lightning is a multiscale phenomenon bridging several length scales, from the nanoscale motion of electrons to the kilometer long lightning channels, and multitudinous energy scales ranging from sub-eV to several tens of MeV. In this presentation, I am going to give an introduction into the physics of electric discharges as well as of production and properties of terrestrial gamma-ray flashes (TGFs), bursts of energetic photons emitted from thunderstorms with quantum energies of up to 40 MeV, making them the highest natural phenomena from Earth with energies beyond those of radioactive decay chains. They are created through the Bremsstrahlung process when relativistic electrons collide with air molecules; however, we miss details on their production as well as of their effects in our atmosphere. I will give an overview of the research in my group including the numerical modelling of discharges and TGFs. We are currently looking into how electrons can reach relativistic electrons in the electric fields relevant for lighting discharges, how TGFs might trigger the production of greenhouse gases as well as how TGFs were produced in the atmosphere of Primordial Earth and how they might have affected the production of amino and carbon acids as a precursor of life. In the very end, I will elaborate on future ideas (including current grant proposals) and of some of my side activities and collaborations associated to the modelling of astrophysical plasmas, theory and modelling in curved space-time and the modelling of discharge phenomena in exoplanet atmospheres. Finally, I will give possible links to the research activity at the TU Dortmund University.