Peter L. Biermann
MPIfR, Bonn; KIT, Karlsruhe; Univ. of Alabama, Tuscaloosa; Univ. of Bonn
Cosmic Lightning and Cosmic Ray Transport
The WAT (wide angle tail) radio galaxies ESO 137-006 and 3C338 show radio filaments including some extending between the two radio tails. If, in analogy to the Parker Solar wind, jets carry a powerful relativistic electric current, driven by gradient drift currents of particles in a p-2 spectrum, Maxwell's continuity equation shows that a temporal variation in jet power would inevitably lead to a localized short-lived charging-up, i.e. a temporary patch of electric field. Progenitors of the observed radio filaments are the relic jets left by repeated episodes of nuclear activity and pushed sideways by the ram pressure, though remaining connected to the broad radio lobes. The Debye shielding distance using the same p-2 spectrum approaches the radio galaxy scale, with a huge total energy content. Here we propose that discharges dissipating the transient patches of electric fields through the filaments illuminate them. The same process will illuminate jets emanating from rapidly rotating young stellar mass black holes (BHs), and lead to lightning. Lightning allows particle spectra of p-3 to p-5 for electrons, as visible in radio data of Galactic filaments, and extragalactic filaments; correspondingly protons and other nuclei have spectra of p-2 to p-4. The steep spectrum allows a steep dependence of residence time on energy/momentum with p-5/3, that is suggested by fits to the AMS spectra for transport in the OB-Super-bubble: Based on earlier ideas here a model is proposed that focusses on the cosmic ray interaction first in the wind shock shell of super giant stars, when the supernova driven shock races through, and second in the OB-Superbubble full of lightning: The two key aspects are i) a much larger column of interaction, allowed because of heavy element enrichment of the interaction zone, and ii) even He, C, and O may have a small secondary contribution, as the difference to the Fe spectrum suggests; this small secondary component is visible in the 3He data. In this model OB-Superbubbles are thunderstorms.