HAWC measurements of the energy spectra of cosmic ray protons, helium and heavy nuclei in the TeV range

TL;DR

This study uses HAWC data to measure the energy spectra of cosmic ray protons, helium, and heavy nuclei in the 10 TeV to 251 TeV range, revealing fine structures that inform cosmic ray origin theories.

Contribution

First measurement of cosmic ray spectra for multiple elemental groups in the TeV range using HAWC data and the Gold unfolding technique.

Findings

Spectra exhibit fine structures within 10 TeV to 251 TeV.

Proton, helium, and heavy nuclei spectra are characterized separately.

Results provide new insights into cosmic ray composition and propagation.

Abstract

Current knowledge of the relative abundances and the energy spectra of the elemental mass groups of cosmic rays in the $10$ TeV - $1$ PeV interval is uncertain. This situation prevents carrying out precision tests that may lead to distinguish among the existing hypotheses on the origin and propagation of TeV cosmic rays in the galaxy. In order to learn more about the mass composition of these particles, we have employed HAWC data from hadron induced air showers in order to determine the spectra of three mass groups of cosmic rays: protons, helium and heavy nuclei with $Z > 2$. The energy spectra were estimated by using the Gold unfolding technique on the 2D distribution of the lateral shower age against the estimated primary energy of events with arrival zenith angles smaller than 45 degrees. The study was carried out based on simulations using the QGSJET-II-04 model. Results are presented for primary cosmic-ray energies from $10$ TeV to $251$ TeV. They reveal that the aforementioned cosmic ray spectra exhibit fine structures within the above primary energy range.