Radio universality and template-based pulse synthesis

Abstract

When discussing radio emission from cosmic ray air showers we commonly make a number of assumptions regardingthe production and propagation physics. Incorporating all of these it should be possible to construct a forward model to predict the radio signal produced by an air shower from simple parameters, an application and generalisation of shower universality to radio emission. In terms of particle detection shower universality focuses on the one-dimensional longitudinal profile, counting only the number of particles. This appears insufficient in the context of radio emission, the particle cascade develops on the scale of traversed atmospheric depth while electromagnetic radiation scales with the geometric trajectories of the sources. Further a real shower extends several radio wavelengths in the lateral directionwhile analyses often assume a point source on the shower axis. Our simulation studies show an unanticipated complexity in the radio output responsible for around 10% variation in the signals. We are still in the process of identifying the relevant quantities and improving our analytical modeling accordingly.