Measurement of the properites of cosmic rays with the LOFAR radio telescope

TL;DR

This paper demonstrates how the LOFAR radio telescope measures properties of high-energy cosmic rays by detecting radio emissions from air showers, providing insights into their origin and composition in the 10^17 to 10^18 eV energy range.

Contribution

It introduces a routine radio detection method for cosmic ray properties using LOFAR, advancing understanding of cosmic ray origins and composition in a key energy range.

Findings

Radio detection accurately measures cosmic ray direction, energy, and type.

LOFAR data constrains models of cosmic ray origin.

Results support a transition from galactic to extragalactic sources.

Abstract

High-energy cosmic rays, impinging on the atmosphere of the Earth initiate cascades of secondary particles, the extensive air showers. The electrons and positrons in the air shower emit electromagnetic radiation. This emission is detected with the LOFAR radio telescope in the frequency range from 10 to 240 MHz. The data are used to determine the properties of the incoming cosmic rays. The radio technique is now routinely used to measure the arrival direction, the energy, and the particle type (atomic mass) of cosmic rays in the energy range from $10^{17}$ to $10^{18}$ eV. This energy region is of particular astrophysical interest, since in this regime a transition from a Galactic to an extra-galactic origin of cosmic rays is expected. For illustration, the LOFAR results are used to set constraints on models to describe the origin of high-energy cosmic rays.