Measurement of the cosmic ray spectrum with the Pierre Auger Observatory

Daniela Mockler

doi:10.1051/epjconf/201920901029

Abstract

The flux of ultra-high energy cosmic rays above 3×1017 eV has been measured with unprecedented precision at the Pierre Auger Observatory. The flux of the cosmic rays is determined by four different measurements. The surface detector array provides three data sets, two formed by dividing the data into two zenith angle ranges, and one obtained from a nested, denser detector array. The fourth measurement is obtained with the fluorescence detector. By combing all four data sets, the all-sky flux of cosmic rays is determined. The spectral features are discussed in detail and systematic uncertainties are addressed.

Highlights

The measurement of the energy spectrum of Ultra-High Energy Cosmic Rays (UHECRs) is key to answer the fundamental questions of the origin and propagation of these particles
The data taking of the Pierre Auger Observatory [1] started in 2004 and the high-quality data taken since led to an unprecedented measurement of the UHECR spectrum
The Fluorescence Detector (FD) records the fluorescence light emitted by the nitrogen molecules that are excited by the secondary particles traversing through the atmosphere as well as the Cherenkov light induced by the secondaries

Summary

Introduction

The measurement of the energy spectrum of Ultra-High Energy Cosmic Rays (UHECRs) is key to answer the fundamental questions of the origin and propagation of these particles. The data taking of the Pierre Auger Observatory [1] started in 2004 and the high-quality data taken since led to an unprecedented measurement of the UHECR spectrum. The precise measurement of the flux, in combination with the mass composition and the distribution of the arrival directions of the particles over the sky, are important ingredients for astrophysical models describing the origin and the propagation of UHECRs. SD is overlooked by 27 optical telescopes distributed into five buildings along the periphery of the array. We present the measurements of the flux of cosmic rays obtained with the four data sets and their combination to the all-sky flux spanning an energy range of almost three decades

Flux measurements with the SD and FD

Findings

Combined energy spectrum