Constraining the cosmic-ray mass composition by measuring the shower length with SKA

TL;DR

This paper proposes using the high-density low-frequency radio measurements from SKA to reconstruct the shower length L, providing new constraints on cosmic-ray mass composition and advancing understanding of the galactic to extragalactic transition.

Contribution

It introduces a novel method to constrain cosmic-ray mass composition by measuring shower length L with SKA's dense antenna array.

Findings

High-resolution radio measurements enable precise L reconstruction.

SKA's antenna density significantly improves mass composition constraints.

Potential to clarify the transition from galactic to extragalactic cosmic rays.

Abstract

The current generation of air shower radio arrays has demonstrated that the atmospheric depth of the shower maximum Xmax can be reconstructed with high accuracy. These experiments are now contributing to mass composition studies in the energy range where a transition from galactic to extragalactic cosmic-ray sources is expected. However, we are still far away from an unambiguous interpretation of the data. Here we propose to use radio measurements to derive a new type of constraint on the mass composition, by reconstructing the shower length L. The low-frequency part of the Square Kilometer Array will have an extremely high antenna density of roughly 60.000 antennas within one square kilometer, and is the perfect site for high-resolution studies of air showers. In this contribution, we discuss the impact of being able to reconstruct L, and the unique contribution that SKA can make to cosmic-ray science.