Analysis optimisation for more than 10 TeV gamma-ray astronomy with IACTs

TL;DR

This paper introduces an optimized analysis technique for H.E.S.S. gamma-ray data, enhancing sensitivity above 10 TeV by improved event reconstruction, gamma-hadron separation, and expanded field-of-view, enabling better detection of high-energy sources.

Contribution

The paper presents a novel analysis method tailored for energies above 10 TeV, including advanced reconstruction and wider field-of-view considerations, improving high-energy gamma-ray detection capabilities.

Findings

Enhanced sensitivity above 10 TeV for H.E.S.S.

Expanded effective field-of-view from 5° to 9°

Demonstrated applicability to hard-spectrum Galactic sources

Abstract

The High Energy Stereoscopic System (H.E.S.S.) is one of the currently operating Imaging Atmospheric Cherenkov Telescopes. H.E.S.S. operates in the broad energy range from a few tens of GeV to more than 50 TeV reaching its best sensitivity around 1 TeV. In this contribution, we present an analysis technique, which is optimised for the detection at the highest energies accessible to H.E.S.S. and aimed to improve the sensitivity above 10 TeV. It includes the employment of improved event direction reconstruction and gamma-hadron separation. For the first time, also extensive air showers with event offsets up to 4.5$^{\circ}$ from the camera centre are considered in the analysis, thereby increasing the effective Field-of-View of H.E.S.S. from 5$^{\circ}$ to 9$^{\circ}$. Key performance parameters of the new high-energy analysis are presented and its applicability demonstrated for representative hard-spectrum sources in the Milky Way.