Optimizing the angular resolution of the HEGRA telescope system to study the emission region of VHE gamma rays in the Crab Nebula

TL;DR

This paper enhances the angular resolution of the HEGRA telescope system to better understand the size of the gamma-ray emission region in the Crab Nebula, using Monte Carlo simulations and comparative measurements.

Contribution

It presents optimized angular resolution techniques for the HEGRA system and constrains the emission region size in the Crab Nebula.

Findings

Angular resolution improved to better than 3' for selected events.

The VHE gamma-ray emission region in the Crab Nebula is less than 1.5' in size.

Comparison with Monte Carlo simulations supports the emission region size estimate.

Abstract

The HEGRA system of imaging atmospheric Cherenkov telescopes provides for specially selected classes of events an angular resolution of better than 3'. By comparing the measured angular distribution of TeV gamma rays from the Crab Nebula with the distribution expected on the basis of Monte Carlo simulations, and with measurements of gamma rays from the point source Mrk 501, we conclude that the rms size of the VHE gamma-ray emission region in the Crab Nebula is less than 1.5'.