# HESS J1826$-$130: A Very Hard $\gamma$-Ray Spectrum Source in the Galactic Plane

## TL;DR

HESS J1826-130 is a very hard gamma-ray source in the Galactic plane with a spectrum indicating acceleration of particles up to hundreds of TeV, likely due to cosmic-ray interactions with molecular clouds.

## Contribution

This paper reports the discovery and spectral analysis of HESS J1826-130, highlighting its unusually hard spectrum and potential hadronic origin involving cosmic-ray interactions.

## Key findings

- Spectral index of 1.6 with a cutoff at 12 TeV.
- No clear counterpart at other wavelengths.
- Likely hadronic origin involving cosmic-ray interactions.

## Abstract

HESS J1826$-$130 is an unidentified hard spectrum source discovered by H.E.S.S. along the Galactic plane, the spectral index being $\Gamma$ = 1.6 with an exponential cut-off at about 12 TeV. While the source does not have a clear counterpart at longer wavelengths, the very hard spectrum emission at TeV energies implies that electrons or protons accelerated up to several hundreds of TeV are responsible for the emission. In the hadronic case, the VHE emission can be produced by runaway cosmic-rays colliding with the dense molecular clouds spatially coincident with the H.E.S.S. source.