Monte Carlo Studies of Geomagnetic Field Effects on the Imaging Air Cherenkov Technique for the MAGIC Telescope Site

TL;DR

This study uses Monte Carlo simulations to analyze how the Earth's geomagnetic field affects the imaging quality of the MAGIC telescope in detecting very high energy gamma-ray induced air showers.

Contribution

It provides the first detailed Monte Carlo analysis of geomagnetic field effects on Cherenkov light images at the MAGIC telescope site, highlighting impacts on gamma-ray detection.

Findings

GF effects degrade low-energy gamma-ray measurements below 100 GeV.

GF influences high-energy gamma-ray observations at TeV energies.

Geomagnetic effects can complicate gamma-ray source imaging.

Abstract

Imaging air Cherenkov telescopes (IACTs) detect the Cherenkov light from extensive air showers (EAS) initiated by very high energy (VHE) gamma-rays impinging on the Earth's atmosphere. Due to the overwhelming background from hadron induced EAS, the discrimination of the rare gamma-like events is vital. The influence of the geomagnetic field (GF) on the development of EAS can further complicate the imaging air Cherenkov technique. The amount and the angular distribution of Cherenkov light from EAS can be obtained by means of Monte Carlo (MC) simulations. Here we present the results from dedicated MC studies of GF effects on images from gamma-ray initiated EAS for the MAGIC telescope site, where the GF strength is ~40 micro Tesla. The results from the MC studies suggest that GF effects degrade not only measurements of very low energy gamma-rays below ~100 GeV but also those at TeV-energies.