Evidence of 100 TeV ${\gamma}$-ray emission from HESS J1702-420: A new PeVatron candidate

TL;DR

This paper reports the first detection of gamma-rays up to 100 TeV from HESS J1702-420, providing strong evidence that it is a PeVatron candidate capable of accelerating cosmic rays to PeV energies.

Contribution

The study presents new H.E.S.S. observations revealing gamma-ray emission up to 100 TeV and discovers a new source component, HESS J1702-420A, enhancing understanding of Galactic cosmic-ray origins.

Findings

Detection of gamma-rays up to 100 TeV from HESS J1702-420

Discovery of a new gamma-ray source component, HESS J1702-420A

HESS J1702-420A has a power-law spectrum extending to 100 TeV without curvature

Abstract

The identification of active PeVatrons, hadronic particle accelerators reaching the knee of the cosmic-ray spectrum (at the energy of few PeV), is crucial to understand the origin of cosmic rays in the Galaxy. In this context, we report on new H.E.S.S. observations of the PeVatron candidate HESS J1702-420, which reveal the presence of gamma-rays up to 100 TeV. This is the first time in the history of H.E.S.S. that photons with such high energy are clearly detected. Remarkably, the new deep observations allowed the discovery of a new gamma-ray source component, called HESS J1702-420A, that was previously hidden under the bulk emission traditionally associated with HESSJ1702-420. This new object has a power-law spectral slope < 2 and a gamma-ray spectrum that, extending with no sign of curvature up to 100 TeV, makes it an excellent candidate site for the presence of PeV-energy cosmic rays. This discovery brings new information to the ongoing debate on the nature of the unidentified source HESSJ1702-420, one of the most compelling PeVatron candidates in the gamma-ray sky, and on the origin of Galactic cosmic rays.