The all-particle energy spectrum of cosmic rays from 10 TeV to 1 PeV measured with HAWC

TL;DR

This paper presents an updated measurement of the all-particle cosmic ray energy spectrum from 10 TeV to 1 PeV using HAWC data, revealing a knee-like feature around tens of TeV, aiding cross calibration of cosmic ray detection methods.

Contribution

The study provides the first update of HAWC's cosmic ray spectrum measurement over two years, utilizing unfolding analysis and the QGSJET-II-04 model to identify spectral features.

Findings

Detected a knee-like feature in the spectrum around tens of TeV.

Extended the energy range of cosmic ray measurements up to 1 PeV.

Provided data for cross calibration between indirect and direct cosmic ray observations.

Abstract

The HAWC observatory is an air-shower detector, which is designed to study both astrophysical gamma-rays in the TeV region and galactic cosmic rays in the energy interval from 1 TeV to 1 PeV. This energy regime is quite interesting for cosmic ray research, since indirect observations overlap with direct measurements, which offers the opportunity for cross calibration and studies of experimental systematic errors in both techniques. One quantity that could help for this purpose is the all-particle energy spectrum of cosmic rays. In this work, we present an update of HAWC measurements on the total cosmic-ray energy spectrum between 10 TeV and 1 PeV. The spectrum was obtained from an unfolding analysis of almost two years of HAWC's data, which was collected from January, 2018 to December, 2019. For the energy estimation, we employed the high-energy hadronic interaction model QGSJET-II-04. As in a previous work of HAWC, published in 2017, we observed the presence of a knee-like feature in the region of tens of TeV.