A Near-Field Interferometry of Cosmic Ray Air Showers with the Square Kilometre Array

Astroparticle Physics, Karlsruhe Institute of Technology, Karlsruhe, Germany — 2Inter-University Institute For High Energies, Vrije Universiteit Brussel, Brussels, Belgium — 3Max-Planck Institut für Astrophysik, Garching, Germany — 4Ludwig-Maximilians-Universität München, München, Germany — 5Deutsches Zentrum für Astrophysik, Görlitz, Germany

With the advent of the low-frequency component of the Square Kilometre Array (SKA-Low), its high antenna density and large frequency bandwidth will allow radio measurements of cosmic ray air showers to be performed with unprecedented accuracy. Current analysis techniques can already reconstruct shower properties with high precision, but are limited by their high computational cost and limited use of the information within the signal. In this work, we showcase that SKA-Low has the potential to perform near-field interferometry by reconstructing the spatial and temporal evolution of the shower with Information Field Theory, a novel Bayesian reconstruction framework that retrieves distributions of field-like quantities from observed signals. We validate our approach with realistic simulated datasets, showing that, through the reconstruction of the shower evolution, we can not only improve our understanding of the mass composition of cosmic rays but also probe the underlying hadronic physics within the shower.