Timing analysis techniques at large core distances for multi-TeV gamma ray astronomy

TL;DR

This paper introduces a timing-based analysis technique for Cherenkov images from extensive air showers, significantly improving angular and core resolution at multi-TeV energies, and proposes a sparse array approach for gamma-ray astronomy above 10 TeV.

Contribution

The paper presents a novel timing analysis method combined with an improved direction reconstruction algorithm for large core distance gamma-ray showers, enhancing resolution and array design for high-energy gamma-ray astronomy.

Findings

Angular resolution improves by up to 40% with timing information.

Core resolution improves by up to 30% using the new technique.

Potential to expand the collection area to over 10 km² with sparse arrays.

Abstract

We present an analysis technique that uses the timing information of Cherenkov images from extensive air showers (EAS). Our emphasis is on distant, or large core distance gamma-ray induced showers at multi-TeV energies. Specifically, combining pixel timing information with an improved direction reconstruction algorithm, leads to improvements in angular and core resolution as large as ~40% and ~30%, respectively, when compared with the same algorithm without the use of timing. Above 10 TeV, this results in an angular resolution approaching 0.05 degrees, together with a core resolution better than ~15 m. The off-axis post-cut gamma-ray acceptance is energy dependent and its full width at half maximum ranges from 4 degrees to 8 degrees. For shower directions that are up to ~6 degrees off-axis, the angular resolution achieved by using timing information is comparable, around 100 TeV, to the on-axis angular resolution. The telescope specifications and layout we describe here are geared towards energies above 10 TeV. However, the methods can in principle be applied to other energies, given suitable telescope parameters. The 5-telescope cell investigated in this study could initially pave the way for a larger array of sparsely spaced telescopes in an effort to push the collection area to >10 km2. These results highlight the potential of a `sparse array' approach in effectively opening up the energy range above 10 TeV.